Easy Vanilla Cake Recipe

In a large bowl, sift flour, baking powder, baking soda, and salt. Set aside. In a measuring jug, mix fresh milk and vinegar and stir to combine. Set aside for at least 5 minutes. 

Preheat oven to 350 degrees F (180 degrees C). Lightly butter and line with parchment the bottom of a 9' x 13'-inch baking pan. Set aside. 

In the bowl of a stand mixer, beat butter and sugar together until light and fluffy. Add and beat in eggs, one at a time, followed by the vanilla flavoring. Gradually add flour mixture alternating with the homemade buttermilk. Mix only until blended.

Pour into the prepared baking pan, and spread until the batter reaches all the edges of the pan. Tap the pan lightly on the counter gently to release any bubbles. 

Bake in the preheated oven for 30 minutes or until a skewer inserted in the cake emerges clean. Cool completely on a wire rack.

While the cake bakes, make the vanilla buttercream: In the stainless steel mixing bowl of the stand mixer, combine egg whites, sugar, and salt. Place over a gently simmering pot of water and gently mix constantly using a silicone spatula until the sugar has dissolved and the egg whites are fully warmed. (You can use a thermometer; pasteurize the egg whites until its temperature reaches 70 degrees F or 21 degrees C.) 

Place in the stand mixer and using the whisk attachment, whisk the warmed egg whites until it forms a meringue with stiff peaks and has cooled to the touch. Add one tablespoon softened butter at a time, whisking until each has been mixed in before adding the next cube. Once all the butter has been added and mixed in, add vanilla flavoring and whisk until light and fluffy. 

When ready to serve, top sheet cake with buttercream frosting using an offset spatula or a spoon. Decorate as desired with sprinkles, melted chocolate, or leave plain. Slice into squares and serve.