Preheat the oven to 350°F (175°C).
Lightly butter a 9-inch (24 cm) baking pan.
In a large bowl, beat 3/4 cup sugar and 5 egg yolks for 5 minutes until the mixture becomes pale yellow.
Gradually fold in the milk, vanilla extract, flour, and baking powder into the egg yolk mixture. Set aside.
In a separate bowl, beat the 5 egg whites until soft peaks form.
Gradually add 1/4 cup sugar to the egg whites and continue beating until the mixture is glossy and stiff.
Gently fold the egg whites into the egg yolk mixture.
Pour the batter into the prepared baking pan.
Bake for 40 to 50 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cake to cool completely on a wire rack.