Preheat your oven to 180°C (350°F). Grease and line two 8-inch round cake pans.
In a mixing bowl, whisk together the eggs and granulated sugar until pale and fluffy.
Sift in the flour and baking powder, then gently fold into the egg mixture.
Add the melted butter and vanilla extract, folding gently until just combined.
Divide the batter evenly between the prepared cake pans and smooth the tops.
Bake for 25-30 minutes, or until the tops are golden and a toothpick inserted comes out clean.
Let the cakes cool in the pans for 10 minutes before transferring to wire racks to cool completely.
Once cooled, whisk the heavy cream with powdered sugar until soft peaks form.
Spread a layer of Biscoff spread on top of one cake layer, then top with half of the whipped cream.
Place the second cake layer on top, then spread the remaining Biscoff on top and the rest of the cream to finish.
Chill the cake in the fridge for at least 30 minutes before slicing and serving.