Line a 9x9" Square tin, and leave to the side for now.
Chop up your chocolate finely, and leave to the side for now.
Add your digestives, mini marshmallows, Reese's pieces, and peanut butter cups to a large bowl. Leave some of the Reese's pieces and peanut butter cups to the side for decorating the top.
In a medium pan, add your golden syrup, and butter, and heat on a medium heat till the butter has melted fully.
Once heated, take off the heat, and pour in your chocolate and peanut butter. Mix together with a spatula until the chocolate has melted fully and everything is mixed together.
Leave the mixture to cool for a minute or two, and then pour into the large bowl with the rest of the ingredients.
Fold together till everything is combined, and then press into the prepared tin. Add the leftover Reese's pieces, and peanut butter cups to the top for the decoration.
Leave to set in the fridge for a couple of hours until set. Once set, chop up and enjoy! x
Notes
This traybake will last in the fridge (if its hot out) for up to two weeks, or on the side (if cooler) for a week as well.
You can use either Milk or Dark Chocolate in this recipe, its up to you. Or, you can even use half and half. I wouldn't recommend White chocolate because of the Golden Syrup and Butter.
If you are struggling with the mixture splitting, its getting too hot. Its also worth having the chocolate in small chopped up pieces so they take less time to melt.
You can half the recipe if you wish for a smaller amount.
The Reese's pieces I used I found in Sainsbury's, and the peanut butter cups were the already unwrapped ones.