Preheat your oven to 350°F (175°C) and prepare your baking pan.
In a mixing bowl, beat eggs and sugar until the mixture triples in volume and becomes pale.
Sift together flour, baking powder, and salt in a separate bowl.
Gently fold the dry ingredients into the egg-sugar mixture.
Add melted butter and vanilla extract, folding until just combined.
Pour half of the batter into the prepared pan and swirl in Biscoff spread.
Pour the remaining batter on top and smooth the surface.
Bake for 25-30 minutes or until a toothpick comes out clean.
Let the cake cool in the pan for 10 minutes before transferring to a wire rack.
Whip the heavy cream with powdered sugar until soft peaks form.
Spread whipped cream on the cooled sponge, and garnish as desired.