Cake Flour (¾ cup): This is non-negotiable. Cake flour has a significantly lower protein content than all-purpose flour, which prevents excess gluten development and guarantees a tender, rollable structure.Large Eggs (4 whole, room temperature): The undisputed structural backbone of the cake. Because there is no baking powder or baking soda, the trapped air in the whipped eggs provides 100% of the dessert's lift.Granulated Sugar (½ cup): Sweetens the crumb and acts as a stabilizing agent during the aggressive egg-whipping process.Pure Vanilla Extract (1 tsp): Adds deep, floral aromatic notes to the otherwise neutral sponge.Fine Sea Salt (¼ tsp): A critical flavor enhancer that balances the sweetness.Melted Unsalted Butter (2 tbsp, slightly cooled): Added at the very end to provide a tiny touch of richness without weighing down the delicate foam structure.