Preheat the oven to 170°C (340°F) and line a 9x9-inch square baking tin with parchment paper.
Melt the butter and dark chocolate in separate bowls, either in the microwave in short bursts or over a pan of simmering water.
165 g unsalted butter, 120 g dark chocolate
Once melted, add them to a mixing bowl with the sugar and whisk until smooth and combined.
360 g caster sugar
Add the eggs one at a time, whisking well after each addition, then stir in the vanilla extract.
2 eggs, 1 teaspoon vanilla extract
Sift the flour, cocoa powder, and salt together, then gently fold into the chocolate mixture until no dry pockets remain. Be careful not to overmix.
75 g cocoa powder, ¼ teaspoon Salt, 120 g plain flour
Fold in the white and dark chocolate chips along with the chopped Toffee Crisp pieces until evenly distributed throughout the batter.
100 g white chocolate chips, 100 g dark chocolate chips, 100 g Toffee Crisp bars
Pour the mixture into the prepared tin and spread it evenly. Bake for around 25 minutes, or until the top looks set and a skewer inserted into the center comes out with a few moist crumbs.
Let the brownies cool in the tin for 5 minutes before transferring them to a wire rack to cool completely. Once cooled, remove the parchment paper.
Melt the dark chocolate and drizzle it over the top of the brownies. Cut the remaining Toffee Crisp bars into small chunks and place one piece on top of each brownie square.
70 g dark chocolate, 100 g Toffee Crisp bars
Allow the brownies to set before cutting into 16 squares. Serve and enjoy rich, fudgy brownies filled with crunchy toffee and chocolate pieces.
Notes
Tips & Tricks
Don't overbake - brownies should be slightly soft in the center for the best fudgy texture.
Use room-temperature eggs for a smoother, well-blended batter.
Melt chocolate slowly to avoid burning or seizing.
If you can't find Toffee Crisp bars, try using Crunchie, Mars, or another caramel-filled bar.
To freeze, wrap individual brownies in cling film and store for up to two months. Thaw before serving.
For an indulgent dessert, warm a brownie and top it with a scoop of vanilla ice cream.