How To Make A Magic 3-Layer Cake In Only 1 Pan

MAGIC CUSTARD CAKE
INGREDIENTS
3 egg, yolks and whites separated
1 tablespoon water
⅓ cup + 2 tablespoons (90 grams) sugar
6 tablespoons (90 grams) melted butter
¾ cup (90 grams) flour
1 teaspoon vanilla extract
Pinch of salt
1½ cups (375 milliliters) milk
Confectioners’ sugar, for dusting (optional)