Sift the cake flour and prepare melted butter using a double boiler.

Mix eggs, sugar, and corn syrup in a bowl. Heat gently over a double boiler to 45–50°C, then whisk.

Whip the mixture at high speed until creamy. Reduce to medium speed for 3–5 minutes to create a dense texture.

Fold in sifted flour gently to avoid deflating the batter. Scrape the sides and bottom of the bowl to ensure no lumps.

Add melted butter and mix lightly. For better incorporation, mix a small portion of batter with butter first, then combine with the rest.

Pour the batter into a lined pan, filling up to 60%. Bake at 180°C for 20–25 minutes.