Step 1

Preheat the oven to 325 degrees F.

Step 2

Grease an 8-inch square baking dish or line it with parchment paper.

Step 3

Separate the egg yolks and the egg whites.

Step 4

Beat the egg yolks with the sugar until light and fluffy.

Step 5

Add the butter and the vanilla to the egg yolk mixture and beat until well-incorporated, about 1-2 minutes.

Step 6

Add the flour to the egg yolk mixture and mix until smooth and well-combined.

Step 7

Slowly start adding the milk to the egg yolk mixture and beat until everything is well-combined.

Step 8

In a separate bowl, beat the egg whites until stiff peaks form.

Step 9

Gently fold the beaten egg whites into the batter until well combined, but not completely folding in the whites. You should still see some white bits floating at the top.

Step 10

Pour the batter into the prepared baking dish and bake until the top is lightly golden, about 40-70 minutes. It should feel firm to the touch, but still jiggle slightly.

Step 11

Allow the cake to cool completely.

Step 12

Dust with the powdered sugar and cut into squares.

Step 13

Serve.