Half Sheet Cakes Recipe

Prepare oven and pans

Position oven racks to center and upper third. Preheat oven to 350°F (175°C). Lightly grease two half-sheet pans (13 x 18 inches) with nonstick spray or oil and dust with 1 tablespoon flour each, tapping out excess. Line pans with parchment if desired for easier removal.

Combine dry ingredients

In a large bowl or stand-mixer bowl, whisk together flour (6 cups), 5 cups granulated sugar, 4 tsp baking powder, 1 tsp baking soda, and 2 tsp salt until evenly distributed.

Cream butter and sugar

In the bowl of a stand mixer fitted with the paddle attachment (or with a large bowl and hand mixer), beat 1.5 cups softened butter on medium speed about 2–3 minutes until creamy. Gradually add the dry mixture in three additions, alternating with milk in two or three additions: add 1/3 of dry mix, mix briefly, add 1 cup milk, mix until combined; repeat until all dry ingredients and milk are incorporated. Scrape bowl as needed.

Add eggs and vanilla

With mixer on low, add eggs one at a time (8 large eggs), beating briefly after each addition to incorporate. Add 3 tablespoons vanilla extract and mix until batter is smooth, scraping sides and bottom to ensure full incorporation, about 30–45 seconds more. Batter will be pourable but thick.

Portion and bake

Divide batter evenly between the two prepared half-sheet pans (use a kitchen scale for precise portioning or about half the batter per pan). Smooth top with a spatula. Bake in the preheated oven: rotate pans front-to-back and swap rack positions halfway through baking for even color. Bake until a toothpick inserted in the center comes out clean and top springs back, about 20–28 minutes (time varies with ovens and pan material).

Cool

Remove pans from oven and set on wire racks. Let cakes cool in pans for 10–15 minutes, then run a thin spatula around edges and invert onto racks or lift with parchment to cool completely. If using parchment, you can leave the cake on the parchment and transfer to racks. Allow to cool to room temperature before frosting (at least 1 hour).

Combine 1 cup sugar and 1 cup water in a small saucepan over medium heat. Stir until sugar dissolves and bring just to a simmer; do not boil vigorously. Remove from heat, stir in 1 teaspoon vanilla, and let cool to warm. Brush or spray lightly over the cooled cake layers to add moisture and extend freshness. Use about 1/3–1/2 cup syrup per half-sheet as needed.

Beat butter

In a clean stand mixer bowl fitted with the paddle attachment, beat 3 cups softened unsalted butter on medium speed 2–3 minutes until pale and airy.

Add sugar gradually

With mixer on low, add sifted powdered sugar in three or four additions (12 cups total), allowing each addition to incorporate before adding more. Scrape bowl as needed to prevent lumps and ensure even mixing.

Adjust consistency and flavor

Add 2 tablespoons vanilla, 6 tablespoons milk or cream, and 1 teaspoon salt. Beat on medium-high for 2–3 minutes until very smooth and spreadable. If frosting is too thin for decorating, add 1–2 tablespoons more powdered sugar or 1–2 tablespoons cornstarch for a stiffer consistency. If too stiff, add up to 2 tablespoons more milk.

Color (optional)

If coloring, divide frosting into bowls and add gel/paste food coloring (as needed, up to 4 teaspoons total across bowls) and mix until uniform.

Level and prepare layers

If the cake tops domed, level them with a long serrated knife or cake leveler so the surface is even. Place one sheet flat on a large work surface or clean tray; if using a serving board or disposable sheet pan for serving, transfer cake onto that surface.

Apply simple syrup

If using syrup, brush a thin, even layer of cooled simple syrup over the cake surface to moisten.

Frost

Using an offset spatula and an angled motion, apply a thin crumb coat of buttercream (about 1/4–1/3 inch) over the entire surface of each half-sheet. Chill the cake for 15–20 minutes to set the crumb coat. Apply a final thicker layer of buttercream, smoothing with a large offset spatula or bench scraper for a clean finish. Use piping tips and bags if you want decorative borders.

Serve or store

For immediate service, cut into squares (half-sheet yields about 56 2x2-inch pieces or 32 2x3-inch pieces depending on portion). Store leftover cake airtight at room temperature up to 2 days, or refrigerated up to 5 days (bring to room temperature before serving). For longer storage, freeze individually wrapped slices up to 1 month.