A classic Latin American sweet indulgence, delicately soaked or layered with rich dulce de leche, pure vanilla, and warm cinnamon.
Whip egg whites with 1/4 cup sugar to stiff glossy peaks; in another bowl, beat egg yolks with remaining 3/4 cup sugar until pale and doubled; fold in milk and vanilla; gently fold whipped whites into yolks alternately with sifted flour and baking powder.
Pour into a greased 23x33cm baking dish; bake at 180°C for 25-30 minutes until golden and a toothpick emerges clean; cool for 30 minutes.
Whisk sweetened condensed milk, evaporated milk, double cream, and rum in a pitcher.
Pierce the top of the cooled sponge cake all over with a fork; slowly pour the three-milk mixture evenly over the entire cake, allowing every drop to absorb.
Cover and chill in the refrigerator for at least 6 hours (or overnight) to become fully soaked and chilled.
Whip double cream with icing sugar until soft peaks form; spread over the soaked cake, dust with ground cinnamon, and garnish with fresh sliced strawberries.