2 cups warm milk
1 1/4 cups powdered sugar
1 cup all-purpose flour
1/2 cup (1 stick) unsalted butter, melted and cooled
4 eggs, separated
1 tablespoon water
2 teaspoons vanilla extract
1/4 teaspoon kosher salt
powdered sugar, as needed, garnish
Preheat oven to 325 degrees F, and lightly grease an (8×8 inch) baking dish with butter or non-stick spray.
In a completely dry bowl or stand mixer, beat egg whites [making sure there is no yolk in the whites] until stiff peaks form, then set aside.
In a separate bowl, beat egg yolks and powdered sugar until thickened and lightened in color.
Add melted butter and 1 tbsp water into ribbony egg yolk mixture until combined, 1 to 2Mins.
Gradually mix in flour until evenly incorporated, then mix in milk and vanilla extract.
Take 1/3 egg whites and fold it gently into batter…Once incorporated, fold in remaining egg whites.
Pour batter into greased baking dish and place in oven.
Bake for 45 to 50Mins, or until center is just set, but still a little jiggly.
Remove from oven and let cool completely.*Optional*: refrigerate to speed up the chilling process.
Slice into bars and dust with powdered sugar to serve.