Funfetti Layer Cake

Name: Funfetti Layer Cake
Prep time: 45 min
Cook time: 25 min
Total time: 1 h 10 min
Cuisine: American
Ingredients: 3 and 3/4 cups (443g) sifted all-purpose flour* (spoon & leveled); 1 teaspoon baking powder; 1 teaspoon baking soda; 1 teaspoon salt; 1 and 1/2 cups (3 sticks; 345g) unsalted butter, softened to room temperature; 1 and 3/4 cups (350g) granulated sugar; 4 large eggs, room temperature; 2 large egg whites, room temperature; 3 teaspoons (15ml) pure vanilla extract; 1 and 1/2 cups (360ml) buttermilk, room temperature*; 3/4 cup (142g) rainbow sprinkles*; 6 cups (700g) sifted confectioners’ sugar; 1/3 cup (80ml) heavy cream; 3 teaspoons (15ml) pure vanilla extract (or use clear imitation vanilla extract for stark white frosting); 1/8 teaspoon salt; optional: additional sprinkles for garnish