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Super chocolatey cookie dough full of M&M’s, making THE most delicious M&M cookie bars ever!

These are deliciously easy bakes that you can make in an afternoon and enjoy so quickly.. cookie bars are 100% one of my favourite bakes to make and I adore them. 

M&M recipes

I love M&Ms more than most chocolates, because I just want to snack on them all of the time. They tend to bake well and stay so bright and colourful, making sure anything looks perfect. The chocolate style cookie base marries so well with the M&M’s. If you eat the cookie bars when they’re still slightly warm, the M&Ms are gooey, crunchy and amazing.

So far I don’t have masses of M&M related recipes because everything would be so similar, but my M&M cheesecake is a curveball amongst these cookie bars along with my M&M cookies and M&M cookie cake

I find that M&Ms always keep their colour well when baking, and you can use any of the M&Ms that you fancy. I tend to just use the regular M&Ms as I prefer them, but don’t worry about even using a mixture! 

Cookie Bar recipes 

I have been after a cookie traybake recipe for SO LONG. I have struggled so many times as a majority of the recipes are american, and therefore in ‘Cup’ measurements, and no offence to anyone…  but I hate cup measurements. I just find them so unreliable and it just doesn’t make sense too me.

I did have to spend plenty of time however googling each weight of ‘cup’ measurement to find out what it was in grams, and when it didn’t entirely make sense I took a random stab at scaling up or down so make it a whole amount, and oh my days THESE ARE SO GOOD.

Cookie bars are genuinely just cookies baked into traybake form and I adore it. They are different to brownies and aren’t cake bars… they are COOKIE bars. The amount of love for a cookie bar is insane. My mini egg cookie bars are always super popular, as well as my caramel gingerbread cookie bars

Cookie Dough

A cookie dough like this is super similar to other cookie bar recipes as well as cookies on my blog – I have endless amounts of cookie dough related recipes now that you will not be lost for ideas. Maybe, there are too many… but the cookie dough is always super similar. 

  • Butter – Whether its baking spread, butter, or a margarine – they all work for cookie bars
  • Sugar – I use a mixture of white granulated sugar and light brown soft sugar for these 
  • Egg – I tend to use medium eggs in my bakes, but you can use one large egg instead of a medium
  • Vanilla – it is always optional, but adds a delicious flavour. 
  • Flour – Always use plain flour in your cookies!! You don’t want self raising flour as it will create a cake like cookie. I do also use cornflour as it adds a nice texture, but you can remove it and add 25g more flour. 
  • Cocoa – I use a strong cocoa powder when baking because I like a really rich chocolate flavour in my chocolate bakes 
  • Raising agents – For these, I use bicarbonate of soda… it’s a key ingredient in a lot of cookie bakes because it creates a good texture 
  • Salt – I always add sea salt to my cookie dough related bakes because it’s delicious, but you can definitely leave it out, or use salted butter

Tips & Tricks 

I always bake my M&M cookie bars into a 9″ square tin as it creates the perfect bake for me. I bake for the same amount of time each time and it creates a delicious slightly soft cookie bar. If you prefer a crunchier cookie however, you just need to bake for a few extra minutes. 

These will last for 4-5+ days at room temp, but you can freeze them for 3+ months after baking. 

If you want to make these but with a plain vanilla cookie dough, you can remove the cocoa powder and add on 100g more plain flour. 

M&M Cookie Bars!

Super chocolatey cookie dough full of M&M's, making THE most delicious M&M cookie bars ever!
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Category: Traybakes
Type: Cookie Bars
Keyword: M&Ms
Prep Time: 10 minutes
Cook Time: 20 minutes
Cooling time: 2 hours
Total Time: 2 hours 30 minutes
Servings: 16 Pieces
Author: Jane's Patisserie


  • 200 g plain flour
  • 50 g cocoa powder
  • 1 tsp bicarbonate of soda
  • 1/2 tsp salt
  • 1 tbsp cornflour
  • 115 g unsalted butter/baking spread
  • 55 g granulated sugar
  • 135 g light brown sugar
  • 1 Medium egg
  • 1/2 tsp vanilla extract
  • 300 g M&Ms


  • Preheat your oven to 190ºc/170ºc fan and line a 9x9inch square tin with parchment paper, and leave to the side for now.
  • In a larger bowl, melt the butter. Add in the two sugars, and whisk for about 2 minutes so the sugar starts to dissolve and the mixture is smooth.
  • Add in the egg and vanilla extract, and mix
  • Add the plain flour, cocoa powder, bicarbonate, salt and cornflour and mix to a cookie dough
  • Add in the dry Ingredients, and all but a small handful of M&Ms, and mix until a thick cookie dough is formed.
  • Press the mixture into the bottom of the tin and press in the handful of M&Ms into the top for decoration.
  • Bake the traybake in the oven for 18-20 minutes, until the top of the cookie bake looks ‘dry’
  • Leave the cookie bake to cool for about 10 minutes, then leave to cool fully on a wire rack. Cut the bake into 4×4 for decent sizes, or 5×5 for smaller ones! Enjoy!


  • I used oodles of Chocolate M&Ms in this recipe, and the colour on them stayed perfect even after baking, but I’m sure it would work with the Crunchy M&M’s, the Peanut M&M’s, or even smarties for example!
  • These delicious beings will last in an airtight container for up to 4-5 days, but honestly, they’ll be eaten before then.
  • You can find a cookie version of this recipe here


Find my other Cookie & Traybake Recipes on my Recipes Page!

You can find me on:

J x

© Jane’s Patisserie. All images & content are copyright protected. Do not use my images without prior permission. If you want to republish this recipe, please re-write the recipe in your own words and credit me, or link back to this post for the recipe.


  1. Sue on October 26, 2022 at 8:09 am

    Hi, can I freeze this dough or the cookies bars as I do not need them straight away? Thanks.

    • Jane's Patisserie on October 27, 2022 at 3:13 pm

      Hiya! Yes absolutely, you can freeze either for up to 3 months! Hope this helps x

  2. Lizzie on April 9, 2022 at 1:06 pm

    Hi these are absolutely brilliant. So easy and tasty. How postable do you think they are? I’ve been looking for bakes I could post to friends in a letterbox size package. These seem quite robust and in squares which is helpful. Do you reckon they would post okay without being destroyed by the time they got to their destination?!

    If not what’s your top bake that’s easy to post and any recommendations on how to package up well.


  3. Harneet on September 6, 2021 at 8:00 pm

    Hi Jane, this is a great recipe. I was just wondering if I could substitute the egg with something else as I do not eat egg? Please let me know, thank you! X

  4. Honor on June 20, 2021 at 11:02 pm

    Hi! Can I use 250g of M&Ms instead? Thank you 😀

    • Jane's Patisserie on June 28, 2021 at 3:35 pm

      Hiya, yes sure!x

  5. Carolann Abouda on May 21, 2021 at 3:54 pm

    5 stars
    Made this today and it was amazing! I was just wondering though is it supposed to sink in the middle? If not how to I prevent this from happening?

  6. Freya on February 21, 2021 at 2:50 pm

    Hi Jane! Hopefully will be making this recipe soon as it looks delicious! I have baking powder but not bicarbonate of soda, could I substitute it? TIA

    • Jane's Patisserie on February 25, 2021 at 2:28 pm

      It may not be the same result – and its not a straight sub. Baking powder you need to use double x

  7. Charl on January 25, 2021 at 10:01 am

    5 stars
    My 7 yr old made these yesterday all by herself and they turned out amazing! Love your recipes, so easy to follow and always good results 😍

  8. Ellie on June 28, 2020 at 10:36 am

    Would you use the same amount of ingredients if using a 8inch round cake tin to make it into a giant cookie rather than in bars?

    • Jane's Patisserie on June 28, 2020 at 5:11 pm

      Yes you can – the depth will increase so the cooking time will also increase x

    • Ellie on June 28, 2020 at 5:38 pm

      Thank you for the reply Jane.
      How much longer should I increase the time for? I have tried to make giant cookies before and they always come out like cakes, they are far too dense. Is there anyway I can stop this from happening? 🙂

    • Jane's Patisserie on June 28, 2020 at 7:33 pm

      Have a look at my mini egg cookie cake, or my M&M cookie cake recipe! x

  9. Frost clan on June 3, 2020 at 1:37 pm

    You have fast become one of my fav go to pages for yummy treats that’s taste just like my favourite cafes/bake shops would serve. I’ve done the Caramac fudge and milky bar cheesecake both turned out amazing, the kids have now picked these to try next. Excited to see how they turn out thank you for sharing all your recipes and tips 😊

    • Jane's Patisserie on June 3, 2020 at 9:31 pm

      Ahh yay!! I hope you and the kids love these too!!

  10. Elliott on May 31, 2020 at 9:22 am

    Im thinking of making these but don’t fancy the chocolate base so was wondering do i just remove the cocoa powder and top up the by that amount?

    • Jane's Patisserie on May 31, 2020 at 12:26 pm

      Yesss, remove the cocoa and top up the flour!!

  11. Kulvinder on May 18, 2020 at 10:53 am


    Can you substitute self raising flour 1:1 with the plain flour /bicarb mixture?

    • Jane's Patisserie on May 18, 2020 at 11:05 am

      Hey! So when using self raising instead of plain/bicarb it isn’t a straight swap – they will rise up more and then maybe sink in again, or even have a slightly cakey texture, but otherwise it should be fine!

  12. Mads on May 6, 2020 at 5:52 pm

    Hi Jane, I’m not able to access cornflour so what would be a good substitute?

  13. Rachael on April 13, 2020 at 4:17 am

    I’m about to try these but I only have crispy M&Ms do you think that would be ok ?
    Also I want to try the oreo cookie bake today too but I do ‘t have the cadbury oreo bar just 8 packs of oreos lol do you think I could substitute the cadbury bar for normal oreos half and choc chipc half?

    Thanks! i’ve tried the mini egg bars before and they went down very well 🙂

    • Jane's Patisserie on April 27, 2020 at 8:35 pm

      Yes definitely they should be fine!! And yeah half oreos and half chocolate chips should be fine!! x

  14. Joyce Ribey on April 19, 2019 at 2:33 am

    I wish these were in metric measurement so we could try them in Canada.

    • Jane's Patisserie on April 19, 2019 at 8:23 am

      They are in metric?

    • A on May 13, 2020 at 4:55 am

      Hi Jane!
      If I wanted to bake these in an aluminium foil tray what size tray would you recommend and would the cooking time change? Thank you!

    • Jane's Patisserie on May 13, 2020 at 8:55 am

      I don’t often bake in foil trays so I’m not sure what sizings are sold – but as close to the actual size is best, and then the timings should be the same!

  15. Josephine on December 16, 2018 at 2:55 pm

    Hi Jane, I love these bars and many of your other recipes! Thank you for sharing as you do. I wondered if these would freeze well? I’d like to make some ahead – I can’t seem to manage to save any for any length of time 😉 xxx

  16. Libby on October 1, 2018 at 2:05 pm

    Oh my goodness these are amazing!!
    I’ve just made them in preparation for a school coffee morning tomorrow, obviously I had to give them a little nibble beforehand and WOW they are delicious, eye look brilliant too so should go down a treat
    This is the second recipe from your blog I’ve tried and both have turned out great so I will certainly be trying more.
    Thank you for sharing x

  17. Dan on June 6, 2018 at 7:38 pm

    Hi Jane
    These were Delicious! Thanks. They went down very well with everyone. I will be making more bars and brownies from your blog in future. Next up… Rolo Cookie Bars

  18. Creme Egg Cookie Bars! - Jane's Patisserie on March 28, 2018 at 2:39 am

    […] Cookie,  along with a looooad of Chocolate to boot. I based this recipe very similarly on my M&M Cookie Bars recipe as its a really good chocolatey recipe. You can easily make these without the extra cocoa […]

  19. Fiona on January 27, 2018 at 9:40 am

    Have been wanting to try some recipes for ages but we live out in the middle east and some brands of chocolate are difficult to find or the imported ones just don’t taste right. M&M’s seem to taste the same wherever they are made.
    We made these today and they were fantastic! Don’t think they will last long!

  20. Jo on August 28, 2017 at 5:44 pm

    Made these last week and they were fabulous!

    I’m planning to make them again with Reese’s Pieces and vegan margarine, so that they’re dairy free. The only downside is that I shall then have to share them with my lactose intolerant husband!

  21. Soft & Chewy M&M Cookie Bars on March 5, 2017 at 8:37 am

    […] additional chocolate in their cookie bars? I spotted this recipe on Pinterest and adapted it from Jane’s Patisserie. Like Jane, I have a few issues when it comes to American recipes as they can be unreliable as she […]

  22. Amy on September 22, 2016 at 10:20 am

    Hi, do you think I could use the same weight of mint aero (either bubbles or normal bar) in this recipe, or would it drastically effect the bake? Thanks!

    • Jane's Patisserie on September 22, 2016 at 10:23 am

      Ummm I’m not sure if I’m honest – it would affect the bake but I don’t know how badly? Maybe only put in one bar/bag and then some mint extract, and normal chocolate chips?

    • Amy on September 22, 2016 at 12:56 pm

      Thanks – shall give it a go! Got to experiment sometimes.

    • Jane's Patisserie on September 22, 2016 at 5:57 pm

      Very true!

  23. Meggan on September 7, 2016 at 11:00 pm

    I made these today for work, it’s R U OK? Day today. I used yellow M&M’s on top and they taste amazing! Although they didn’t turn out as fudge-y as they look in the pictures- mine are more cake-y. Any tips?

    • Jane's Patisserie on September 7, 2016 at 11:02 pm

      Mine weren’t really fudgey, just more cookie like.. Maybe bake for a bit longer?

    • Meggan on September 14, 2016 at 7:12 am

      Ok thanks- I’ll give that a try next time!

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