Step 1: Preheat the Oven - Begin by preheating your oven to 350°F (175°C).
Step 2: Prepare the Pans - Grease and flour two 9-inch round cake pans.
Step 3: Cream Butter and Sugar - In your stand mixer bowl, combine the softened butter and sugar. Beat until light and fluffy, about 4-5 minutes.
Step 4: Add Eggs and Yolks - Add the eggs and yolks one at a time, mixing well after each addition.
Step 5: Incorporate Dry Ingredients - Whisk together flour, baking powder, and salt. Gradually add to the wet ingredients, mixing on low speed until just combined.
Step 6: Mix in Buttermilk and Vanilla - Slowly pour in buttermilk and vanilla extract. Mix until smooth, being careful not to overmix.
Step 7: Divide and Bake - Evenly divide the batter between the pans. Bake for 25-30 minutes, or until a toothpick comes out clean.
Step 8: Cool the Cakes - Let the cakes cool in the pans for 10 minutes, then transfer to a cooling rack.
Step 9: Frost and Enjoy - Once cooled, frost with your favorite frosting and serve.
