• Preheat oven to 350°F. Grease the inside of your cake pans with butter and then dust with flour, or spray with a floured non-stick baking spray.
• Melt the 10 tablespoons of butter in the microwave, then set aside and let it cool slightly.
  10 tbs unsalted butter
• Combine flour, baking powder, baking soda, salt, and 1 ½ cups sugar in a large bowl; set aside.
  2 ½ cups cake flour, 1 ¼ teaspoon baking powder, ¼ teaspoon baking soda, ¾ teaspoon salt, 1 ¾ cup sugar
• Separate the egg whites and egg yolks. You will use all 6 yolks and 3 of the egg whites separately. *
  3 large eggs, 3 large egg yolks
• Whisk buttermilk, melted butter, oil, vanilla, and the 6 egg yolks until well combined, set aside
  1 cup buttermilk, 3 tbs vegetable oil, 2 teaspoon vanilla
• Using a stand mixer or electric hand mixer and the whisk attachment, whisk egg whites and cream of tartar on medium speed until foam appears (about 1 minute). Then whisk on high until the egg whites become cloud-like (1-2 minutes).
  ⅛ teaspoon Cream of Tartar
• Slowly add the remaining ¼ cup of sugar to the egg whites and whisk until stiff peaks form (~3 minutes). The egg whites will have a satiny sheen. Move egg whites to a different bowl.
• In the stand mixer bowl with the paddle attachment, add the flour mixture. While mixing on low speed, slowly add the buttermilk mixture, then increase the speed to medium-high and make sure it is fully incorporated.
• Using a large spoon or rubber spatula, fold in, by hand, ⅓ of the egg white mixture into the batter. Then carefully fold in the remaining egg white mixture, making sure there aren’t any white streaks when done. Fold in the sprinkles.
  ¾ cup Jimmy Sprinkles
• Pour the batter into the prepared cake pans. Bake for 20-25 minutes, or until a toothpick inserted comes out clean. If baking more than one cake layer at a time, bake the cakes on the same oven rack to ensure even baking.
• Let the cakes cool completely before frosting.

Frosting

• In a bowl of a stand mixer, or with a hand mixer, beat butter on medium-high speed until fluffy.
  1 cup butter
• Alternate between adding powdered sugar and heavy cream, mixing in everything until fluffy. Then mix in the vanilla and salt.
  5 cups powdered sugar, 1 tbs vanilla, 5 tbs heavy cream, Pinch of salt
• Turn the mixer to high and beat for 30 seconds to add volume.
• Fold in sprinkles by hand.
  ½ cup Jimmy Sprinkles
• Frost cake.