Preheat your oven to 180°C (350°F).
In a large mixing bowl, beat the eggs and sugar until pale and fluffy.
Gradually fold in the flour and baking powder until just combined.
Stir in the melted butter and vanilla extract, being careful not to deflate the batter.
Pour the batter into a lined 9-inch round cake tin and smooth the top.
Bake for 25-30 minutes or until a toothpick inserted comes out clean.
Allow the cake to cool in the tin for 10 minutes, then transfer to a wire rack.
Once cooled, slice the cake in half horizontally.
Whip the heavy cream with powdered sugar until soft peaks form.
Spread a generous layer of Biscoff on one half of the cake, followed by whipped cream.
Place the top half of the cake on, then spread more Biscoff and cream on top.
Chill the assembled cake for 30 minutes to set before serving.