Preheat oven to 350°F. Spray three 8 inch cake pans with non-stick baking spray. Place an 8 inch parchment circle on the bottom of the pans and spray again.
In a mixing bowl, sift the flour, baking powder, baking soda, and salt together.
3 ½ cup All-purpose flour, 2 ½ teaspoon Baking powder, ½ teaspoon Baking soda, 1 teaspoon Salt
Using a mixer, beat the butter, oil, and sugar for 3 minutes on high speed. Then, add in vanilla extract and sour cream and mix on medium until combined. Add in the eggs one at a time and mix on medium until combined.
1 cup Unsalted butter, 2 tablespoon Oil, 1 ¾ cup White granulated sugar, 1 tablespoon Clear vanilla extract, ½ cup Sour cream, 4 Large eggs
Add ⅓rd of the dry ingredients and half of the buttermilk and mix on low speed. Add another ⅓rd of the dry ingredients and the rest of the buttermilk. Finish with the rest of the dry ingredients.
1 cup Buttermilk
Take off the mixer. Add in the sprinkles and fold them in with a rubber spatula.
⅔ cup Rainbow sprinkles
Pour batter evenly through the 3 cake pans using a kitchen scale. Bake for 18-23 minutes. Cake is done when a toothpick inserted comes out clean.
Allow cakes to sit for 10 minutes in the pan. Then, transfer to cooling racks. Allow them to cool completely before frosting.