Ingredients
Scale
- 3 cups all-purpose flour
- 1 ½ teaspoons baking powder
- ¾ teaspoon baking soda
- 1 teaspoon salt
- 1 cup unsalted butter, softened
- 2 cups granulated sugar
- 4 large eggs, room temperature
- 1 tablespoon vanilla extract
- 1 ¼ cups buttermilk, room temperature
- 2 tablespoons vegetable oil
- 1 cup unsalted butter, softened
- 3 ½ cups powdered sugar, sifted
- ½ cup unsweetened cocoa powder
- 3–4 tablespoons heavy cream or whole milk
- 1 teaspoon vanilla extract
- ¼ teaspoon salt
Instructions
- Step 1: Preparation and Preheating Preheat your oven to 350°F (175°C). Grease a 9×13 inch baking pan thoroughly with butter or non-stick cooking spray. For even easier removal, you can line the bottom with parchment paper, leaving a slight overhang on the sides. Set the pan aside while you prepare the batter.
- Step 2: Creaming the Butter and Sugar In a large mixing bowl or the bowl of a stand mixer, beat the softened butter and granulated sugar together on medium-high speed. Continue mixing for about 3-5 minutes until the mixture looks pale, light, and fluffy. This step incorporates air, which is vital for a light cake texture.
- Step 3: Adding Eggs and Aromatics Add the eggs one at a time to the butter mixture, beating well after each addition. Scrape down the sides of the bowl to ensure everything is incorporated. Mix in the vanilla extract and the vegetable oil until the batter is smooth and uniform.
- Step 4: Mixing Dry and Wet Ingredients In a separate medium bowl, whisk together the flour, baking powder, baking soda, and salt. Reduce the mixer speed to low. Alternately add the dry ingredients and the buttermilk to the butter mixture, starting and ending with the dry ingredients. Mix only until just combined; overmixing at this stage will result in a tough cake.
- Step 5: Baking the Cake Pour the batter into the prepared baking pan and smooth the top with a spatula. Bake for 28-32 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs. Remove the cake from the oven and let it cool completely in the pan on a wire rack.
- Step 6: Whipping the Chocolate Buttercream While the cake cools, prepare the frosting. Beat the softened butter for 2 minutes until creamy. Add the powdered sugar, cocoa powder, heavy cream, vanilla, and salt. Start the mixer on low to avoid a sugar cloud, then increase to medium-high. Whip for 3-4 minutes until the frosting is light, airy, and spreadable. Add more cream if the frosting is too stiff.
- Step 7: Frosting and Serving Once the cake is entirely cool to the touch, dollop the chocolate buttercream over the top. Use an offset spatula to spread the frosting to the edges, creating decorative swirls as you go. Slice into squares and serve directly from the pan.
- Cook Time: 50 minutes