White velvet buttermilk cake

Name: White velvet buttermilk cake
Prep time: 10 min
Cook time: 30 min
Total time: 70 min
Ingredients: 12 oz cake flour; 12 oz granulated sugar; 1 tsp salt; 1 Tbsp baking powder; 1/2 tsp baking soda; 5 oz egg whites, room temperature; 4 oz vegetable oil; 10 oz buttermilk, room temperature or slightly warm; 6 oz butter, unsalted and softened; 2 tsp vanilla