Preheat the oven to 180°C (356°F) and line a baking tray with parchment paper.

Whisk 100 g egg yolks with 60 g caster sugar until the mixture is light and pale.

Whisk 1 teaspoon vanilla extract into the pale egg-yolk mixture.

Sift 55 g all-purpose flour, 25 g corn flour, 20 g cocoa powder, and 2 g baking powder into the yolk mixture.

Fold the dry ingredients gently into the yolk mixture until no dry streaks remain.

Combine 55 ml milk with 45 g melted butter in a small bowl.

Fold the milk and butter mixture gently into the chocolate yolk batter until smooth.

Whisk 200 g egg whites until foamy, then gradually whisk in 70 g caster sugar.

Whisk the sweetened egg whites until stiff peaks form.

Fold one-third of the whipped egg whites into the chocolate batter to loosen it.

Fold the remaining whipped egg whites into the batter gently until evenly combined.

Spread the batter evenly over the lined baking tray.

Bake the sponge at 180°C (356°F) for 14 minutes, until springy to the touch.

Remove the sponge from the tray and let it cool completely on a clean kitchen towel.

Spread 150 g Biscoff spread in an even layer over the cooled sponge, leaving a small border around the edges.

Roll the filled sponge tightly from one short end into a log.

Refrigerate the Biscoff Swiss roll for at least 60 minutes before slicing and serving.