Ingredients

Cake:
5 egg whites
1 cup milk
1/2 cup oil
1/2 cup (1 stick) butter
2 cups sugar
1 tablespoon baking powder
1 teaspoon salt
2 teaspoons vanilla extract
3 cups flour
Frosting:
6 1/2 cups powdered sugar
1 cup (2 sticks) butter, room temp
2 teaspoons vanilla extract
1/4 teaspoon salt
2 tablespoons milk
Instructions

For Cake:
Preheat oven to 350 degrees F (180 C) and grease 3 8-in cake pans with oil. Pour egg whites into bowl of stand mixer and beat until they form stiff peaks. In separate bowl, cream butter and sugar. Add all other ingredients and mix until smooth.
Now gently fold in the stiff egg whites to the batter just until evenly combined. Divide batter into pans as evenly as possible. Bake for 25 - 35 minutes until toothpick inserted in center comes out clean. Cool completely before frosting.
For Frosting:
Beat butter in a large mixing bowl until creamed. Add vanilla, salt, and powdered sugar one cup at a time. Add milk beat until light and fluffy. Add more milk as needed for frosting consistency.
Assemble:
To assemble, spread frosting on one of the cakes and layer a second on top. Repeat for next cake and place the third layer on top. Frost the top