Ingredients
Scale
- 225g unsalted butter, softened
- 150g light brown sugar
- 75g granulated sugar
- 2 large eggs, room temperature
- 1 tsp vanilla extract
- 270g plain flour
- 1 tsp bicarbonate of soda
- 1 tsp salt
- 200g chocolate chips (plus 20g extra for topping)
- 100g Digestive biscuits, broken into pieces (or graham crackers for US bakers)
- 2 x 200g milk chocolate bars
- 1/2 tub marshmallow fluff (approximately 120g)
Instructions
- Prepare your workspace: Preheat your oven to 150°C (300°F) fan-forced or 170°C (340°F) conventional. Line your 8×8 inch square baking tin with parchment paper, leaving some overhang on the sides for easy removal later.
- Make the cookie dough base: In a large mixing bowl, combine the softened butter, light brown sugar, and granulated sugar. Whisk vigorously until the mixture becomes light and fluffy, about 2-3 minutes. Add the eggs and vanilla extract, then mix until fully incorporated and smooth.
- Add dry ingredients: Gently fold in the plain flour, bicarbonate of soda, and salt until just combined. Be careful not to overmix at this stage. Add 200g of chocolate chips and the broken digestive biscuit pieces, folding them through until evenly distributed throughout the dough.
- Layer the base: Take approximately half of your cookie dough and press it into an even layer in the bottom of your prepared baking tin. This will form the foundation of your bars.
- Add chocolate layer: Place your chocolate bars directly on top of the cookie dough base, breaking them if necessary to create a complete layer that covers the dough.
- Add marshmallow layer: Carefully spoon the marshmallow fluff over the chocolate layer and gently spread it into an even layer. This can be tricky as the fluff is sticky, so use a lightly oiled spatula to help with spreading.
- Top layer assembly: Take the remaining cookie dough and divide it into small portions. Flatten each portion between your palms and arrange them on top of the marshmallow layer. Don’t worry about creating a perfect seal—the gaps where marshmallow peeks through will create beautiful caramelized spots during baking.
- Final touch: Sprinkle the additional 20g of chocolate chips over the top layer of cookie dough.
- Bake: Place your tin in the preheated oven and bake for 35-45 minutes, or until the top is golden brown and the center no longer wobbles when you gently shake the tin.
- Cool completely: This is crucial! Allow the bars to cool completely in the tin before attempting to remove or cut them. This will take at least 2 hours. The bars will continue to set as they cool.
- Slice and serve: Once completely cooled, use the parchment paper overhang to lift the bars out of the tin. Place on a cutting board and slice into 16 even squares with a sharp knife.
Notes
Prep Time: 15 minutes | Bake Time: 35-45 minutes | Cooling Time: 2 hours | Total Time: 3 hours | Yield: 16 bars