Preheat the oven to 200C/180C Fan/Gas 6. Line an 8 inch square baking tin.
Combine the melted butter, Biscoff spread, granulated sugar and light brown sugar in a large mixing bowl or the bowl of a stand mixer. Combine on high speed for 3-5 minutes. Add the eggs and vanilla and combine again.
Fold in the flour, baking powder, chopped white chocolate and Biscoff biscuits, until all combined. Pour into the lined tin.
In a small bowl, whisk together the Biscoff spread, cream cheese, egg and sugar until smooth. Pour over the blondie batter.
Optional: Put 1 tbsp Biscoff spread in a small bowl and microwave for 20-30 seconds, until runny! Use a teaspoon to drizzle this over the cheesecake layer in diagonal lines. Then use the spoon to 'feather' the melted Biscoff - essentially drag the spoon in the opposite direction of the diagonal drizzle. Scatter over some Biscoff biscuits and bake 30-35 minutes.
Let cool completely before slicing!
