Birthday Cake Recipe

Prepare and Preheat

Position oven racks in the center and preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans (or three 8-inch pans) and line bottoms with parchment rounds.

Whisk dry ingredients

In a large bowl, whisk together 3 cups all-purpose flour, 2 cups granulated sugar, 2 tsp baking powder, 1 tsp baking soda, and 1 tsp fine salt until evenly combined.

Cream butter and sugar

In the bowl of a stand mixer fitted with the paddle attachment, beat 1 cup room-temperature unsalted butter and 1 cup sugar (from the dry ingredients) on medium speed for 2–3 minutes until light and fluffy. Scrape down the bowl as needed.

Add eggs and oil

Add the 4 large eggs one at a time, beating about 20–30 seconds after each addition until incorporated. Mix in 1 tablespoon vegetable oil to help keep the cake moist.

Alternate milk and flour

With the mixer on low, add the dry ingredients in three additions alternating with the milk and buttermilk: add one-third of the dry mix, then half of the combined 1 cup whole milk + 1 cup buttermilk, then another third of the dry mix, then the remaining milk mixture, finishing with the last third of the dry mix. Mix just until combined after each addition; avoid overmixing.

Add vanilla

Fold in 2 tsp pure vanilla extract until uniform.

Portion and bake

Divide batter evenly between prepared pans, smoothing tops. Bake in preheated oven for 25–35 minutes (for 9-inch pans) or 22–28 minutes (for 8-inch pans), until a toothpick inserted in the center comes out with a few moist crumbs and the cakes spring back lightly when pressed.

Cool

Allow cakes to cool in pans on a wire rack for 10–15 minutes. Run a thin knife around the edges, invert onto the rack, remove parchment, and cool completely (about 1 hour) before frosting.

Combine 1 tablespoon granulated sugar and 2 tablespoons water in a small saucepan. Warm over low heat, stirring until sugar dissolves. Remove from heat and stir in 1/2 teaspoon vanilla if using. Cool slightly. Brush or drizzle syrup over the cut surfaces of each cake layer after leveling to add moisture (about 1 tablespoon syrup per layer).

Beat butter

In a clean large bowl or stand mixer, beat 2 cups room-temperature unsalted butter on medium speed for 2–3 minutes until smooth and slightly pale.

Add powdered sugar

With the mixer on low, gradually add 6 cups powdered sugar, about 1 cup at a time, mixing after each addition until incorporated and dust has mostly disappeared. Scrape the bowl as needed.

Flavor and adjust consistency

Add 2 tsp pure vanilla extract, 1/4 tsp fine salt, and 4 tablespoons heavy cream (or whole milk). Increase mixer speed to medium-high and beat for 3–4 minutes until light and fluffy. If frosting is too thick, add 1 tablespoon more cream at a time; if too thin, add 1/2 cup more powdered sugar.

Coloring (optional)

If desired, divide frosting into portions and tint with gel or paste food coloring to decorate. Mix until color is even.

Level and layer

If cakes have domed, level the top with a serrated knife or cake leveler. Place the first layer on a cake plate or turntable. Brush the cut surface with the prepared simple syrup (about 1 tablespoon).

Fill

Pipe or spread an even layer (about 3/4 to 1 cup) of vanilla buttercream over the first cake layer, leaving about 1/4 inch from the edge to prevent overflow. Place the second layer on top and repeat syrup and filling if making more than two layers.

Crumb coat

Apply a thin layer of frosting over the top and sides to seal in crumbs (about 1/2 to 1 cup). Chill the cake in the refrigerator for 15–30 minutes to set the crumb coat.

Final frost

Apply a thicker, even final coat of frosting using an offset spatula or bench scraper for smooth sides. Reserve some frosting for piping if desired.

Decorate

Press sprinkles around the base or over the top, pipe rosettes or borders with reserved frosting, and add fresh berries or edible decorations as desired. Chill briefly (10–15 minutes) to set decorations before serving. Return to room temperature 30 minutes before serving for best texture.