Folding Whipped Whites for an Open Sponge

A tres leches needs a light, open crumb so it can drink the soak without collapsing into paste. Separating the eggs is the key: beat the yolks with most of the sugar until pale and thick, build the batter, then whip the whites separately to firm, glossy peaks with the remaining sugar. Fold the whites in two additions, cutting down through the centre and lifting gently so you keep the air you just built. The aerated batter bakes into a fine, springy sponge full of tiny channels — exactly the structure that absorbs a three-milk bath evenly and stays tender rather than dense.