Ingredients
Method
- Preheat your oven to 350°F and grease a 13x18-inch half-sheet pan.
- In a large bowl, cream together the butter, oil, and sugar until light and fluffy.
- Beat in the eggs one at a time, then mix in the vanilla extract.
- In a separate bowl, whisk the flour, baking powder, baking soda, and salt.
- Alternately add the dry ingredients and buttermilk to the wet mixture, starting and ending with the flour.
- Pour the batter into the prepared sheet pan and smooth the top with a spatula.
- Bake for 22-25 minutes, or until a toothpick inserted in the center comes out clean.
- Allow the cake to cool completely in the pan on a wire rack.
- For the frosting, beat the softened butter until creamy, then gradually add the powdered sugar and heavy cream.
- Divide the frosting into three bowls; dye one red, one blue, and leave one white.
- Dollop the colored frostings randomly over the cooled cake and swirl with a knife or offset spatula.
- Top with festive sprinkles and slice into squares to serve.
Notes
For best results, ensure all dairy ingredients are at room temperature to create a smoother batter.
- Do not overmix the batter; mix just until the flour disappears to keep the cake tender.
- To make ahead, bake the cake a day in advance and store it unfrosted at room temperature, covered tightly with foil.
- If you don't have buttermilk, add 1 tablespoon of lemon juice to 1 cup of milk and let it sit for 5 minutes.