S’mores Cookie Bars!

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Gooey Chocolate Chip Cookie, Gooey Vanilla Marshmallow, make THE most Delicious S’mores Cookie bars ever!

Ohhh so like.. yeah. Cookie Bars happened again! I honestly couldn’t resist. I’ve actually baked these beauties several times, getting them slightly more perfect each time. I tried these in quite a few different ways, and honestly, this one stuck. How could you not love Marshmallow and Cookies together?! If you like S’mores then you will love these. Honestly… biscuit, marshmallow, and chocolate together is heaven. So imagine a gooey, chocolatey cookie together with gooey marshmallow. MY IDEA OF HEAVEN.

These would suit being more towards Halloween and Bonfire night, but I just couldn’t resist posting them now. I recently made my No-Bake S’mores Cheesecake again, along with my S’mores Cake for a party and everyone said how good a cookie version would be… so I knew I should finally post this recipe!

I went for my usual cookie bar style recipe, as I have also used in my Mini Egg Cookie Bars and Rolo Cookie Bars. The baking time is somewhere in the middle of these two recipes however… It’s hard to explain sometimes, but the Marshmallow Fluff makes the cookies gooier, and stops them drying out like the Rolo Cookie Bars do. The Mini Egg Cookie Bars can often dry out a lot more as there isn’t anything in there to keep them very gooey, so the Marshmallow Fluff is a dream.

I love anything S’mores as I have said, but these are just DELIGHTFUL. You need to split the cookie dough into two sections… two thirds and one third. It can be a little bit faffy, but you need to press down the first lot of cookie dough so its even (often easier to use your hands) and then spread the marshmallow fluff on top. The problem is, marshmallow fluff is so sticky, its easier to microwave it for 20 seconds so its spreadable! Then comes the problem of putting the next third of cookie dough on. I rolled mine out onto some clingfilm, so that I could turn the layer onto the marshmallow fluff evenly! It’s awkward, but SO WORTH IT. If in doubt, blob bits of cookie dough all over the marshmallow fluff.

S'mores Cookie Bars

Gooey Chocolate Chip Cookie, Gooey Vanilla Marshmallow, make THE most Delicious S’mores Cookie bars ever!
5 from 1 vote
Print Pin Rate
Category: Dessert
Type: Cookie Bars
Prep Time: 10 minutes
Cook Time: 20 minutes
Total Time: 30 minutes
Servings: 16 Pieces
Author: Jane's Patisserie


  • 275 g Plain Flour
  • 1 tsp Bicarbonate of Soda
  • 1/2 tsp Salt
  • 1 tbsp Cornflour
  • 115 g Unsalted Butter/Stork
  • 100 g Granulated Sugar
  • 100 g Light Brown Sugar
  • 1 Medium Egg
  • 1/2 tsp Vanilla Extract
  • 300 g Milk/Dark Chocolate
  • 1x tub Marshmallow Fluff


  • Preheat your oven to 190C/170C Fan and line a 9x9inch Square Tin with parchment paper, and leave to the side for now.
  • Whisk/Mix the Plain Flour, Bicarbonate, Salt and Cornflour together so its evenly distributed – leave to the side.
  • 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 the Vanilla, and whisk again briefly till smooth. (I used an electric whisk)
  • Add in the Dry Ingredients, and mix till a cookie dough is formed. Add in the Chocolate Chips and mix with a spatula until they’re spread through the cookie dough evenly.
  • Press two thirds of the the mixture into the bottom of the tin. Microwave the marshmallow fluff for 20-30 seconds and spread over the cookie dough.
  • Spread/cover the marshmallow fluff layer in the other third of the cookie dough. It might be hard to spread it, so I rolled it out onto some cling film, and then turned it onto the marshmallow layer to make it even. Bake the traybake in the oven for 20-25 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!


  • If you try to use actual marshmallows, they will boil and basically disappear into the cookie bars. Marshmallow fluff is usually found in the supermarkets near the Nutellas and Jams etc, and its quite commonly available!
  • These delicious beings will last in an airtight container for up to 4 days, but honestly, they’ll be eaten before then.
  • You can use whatever chocolate you want in the middle – but I used Dark Chocolate Chips. Milk or White work well, or even a flavoured chocolate!
  • Try Microwaving them when they’ve cooled if you want a gooey cookie, or even add a scoop of ice cream!
  • This post was not inspired by anyone in particular – but I took inspiration from photos on Pinterest/Instagram and just has a go at it!
Nutrition Facts
S'mores Cookie Bars
Amount Per Serving
Calories 168 Calories from Fat 54
% Daily Value*
Fat 6g9%
Saturated Fat 3g19%
Cholesterol 25mg8%
Sodium 158mg7%
Potassium 30mg1%
Carbohydrates 26g9%
Sugar 12g13%
Protein 2g4%
Vitamin A 195IU4%
Calcium 11mg1%
Iron 0.9mg5%
* These are only estimates and can vary dependant on brands of ingredients and serving sizes.


Find my other Cookie and Cookie Bar 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.

About Author

Hiya! I'm Jane, and I adore baking, cooking and all things delicious. I'm also partial to homewares, lifestyle posts and more!


  • Gillian
    May 26, 2020 at 1:30 pm

    What size in grams is the tub of marshmallow fluff please?

  • Drew
    September 8, 2019 at 12:45 pm

    Are you able to make these in a rectangular tray rather than a square one? My square one has disappeared

    • Jane's Patisserie
      September 8, 2019 at 4:42 pm

      Changing the tin will change the baking time, so keep an eye on it. The volume of a differently shaped tin can also be drastically different!

  • Annie
    April 4, 2019 at 3:55 pm

    Can I make these and freeze them??

    • Jane's Patisserie
      April 4, 2019 at 9:36 pm

      I’ve never frozen these particular ones, but I believe you can! Most cookies you can, the only bit I was unsure of was the marshmallow fluff factor!

  • Julie H
    July 16, 2018 at 9:04 am

    5 stars
    I made these for work, they had all gone by 11o/c! Everyone loved them, including someone who doesn’t like marshmallow. They weren’t as firm as yours, but I’m putting that down to the hot weather. Making my second batch tonight for my daughters work 😍

  • Louise
    November 14, 2017 at 11:44 pm

    Hi Jane,
    These look delicious! Have just ordered some Marshmallow Fluff and am going to make them next week!
    Please can I just ask how you got your bars to look like in the pictures if you rolled out the top layer of cookie dough and placed it on top? You can see the Fluff on top of the bars in your pictures? Or did you blob the Fluff on top? Sorry if it’s a silly question, just want to make sure I do them perfectly x

    • Jane's Patisserie
      November 15, 2017 at 9:18 pm

      The layer of cookie dough on top is quite thin, and the marshmallow naturally breaks through in weaker areas. It doesn’t need to be perfect.

    • Louise
      November 15, 2017 at 9:59 pm

      Great, thank you!

  • Sarah Beevers
    November 8, 2017 at 10:38 am

    Hi there – I’ve not been able to source Marshmallow fluff too easily – has anyone tried this simply with marshmallows in their place?

    • Jane's Patisserie
      November 8, 2017 at 6:21 pm

      Whereabouts are you from? As noted in the tips and ideas section on the post, actual marshmallows will just dissolve and cause the traybake to not bake so well.

    • Sarah Beevers
      November 8, 2017 at 7:53 pm

      I’m from Scotland!

  • Carolyn
    September 25, 2017 at 9:35 pm

    These look amazing Jane! I’m excited to try the recipe for myself!

    Carolyn x
    Faithfully Carolyn


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