Preheat the oven to 325 F and grease an 8x8-inch baking dish.
Separate the eggs.
Beat the egg yolks in a large bowl with the sugar on medium speed until they're light and fluffy, about 5 minutes.
Add the butter and vanilla to the egg and sugar mixture and beat it on medium speed for an additional 1 minute until the combination is an even consistency.
Add the flour and beat the mixture on low speed for 1 minute to ensure that it's fully mixed into the wet batter.
Slowly add the warmed milk to the flour mixture, beating in between each addition to incorporate it.
Beat the egg whites in a separate bowl on medium speed until stiff peaks appear – this takes about 3 to 5 minutes.
Gently whisk the egg whites into the batter.
Bake your cake at 325 F for 45 minutes until the top is golden brown, the sides are pulling away, and the center jiggles slightly.
Cool the cake before cutting.
Serve your magic cake with whatever toppings you like.
