Start by melting the Biscoff spread for about 30 seconds - 1 minute in the microwave, until loosened. Spread this over a lined 8 inch square tin (or similar) and freeze for at least an hour.
Preheat the oven to 200C/180C Fan/Gas 6. Line an 8" Square Pan.
Start by melting the dark chocolate: break up the dark chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn’t burn. Set aside to cool a little whilst doing the rest:
Combine the melted butter, granulated sugar and light brown sugar in a large bowl/bowl of a stand mixer – on a medium speed for 3-5 minutes.
Add in the eggs and vanilla and mix again. Then, checking first that the chocolate isn't so hot as to cook the eggs, add it in and keep mixing.
Add the flour and cocoa powder and fold in gently. Add in the white chocolate chunks and some roughly chopped Biscoff biscuits (about 6). Gently fold together.
Pour half the batter into the prepared tin. Add the layer of Biscoff spread and pour the remaining batter on top. Bake for 30-35 minutes. Let cool on a wire rack before slicing and serving.
