This easy lemon sheet cake is bursting with bright, citrusy flavor from fresh lemon juice and zest in both the fluffy cake and zippy buttercream frosting. This one-layer version of my lemon cake is moist, flavorful, and perfect for feeding a crowd-- no layering or fancy tools required.
In a large bowl with a handheld mixer or the bowl of a stand mixer fitted with the paddle attachment, beat the butter, sugar, and lemon zest on medium-high speed until light and fluffy (about 3 minutes).
1 cup (227g) unsalted butter, 1 and ¾ cup (350g) granulated sugar, zest of 2 lemons
Add each egg, one at a time, beating on medium-high speed until fully incorporated, scraping down the sides as necessary. Add the vanilla extract and beat again until combined.
4 large eggs, 3 teaspoons vanilla extract
Stir the lemon juice into the milk. Scrape down the sides of the mixer bowl and turn the mixer speed to low. Add the flour in 2 additions, alternating with the milk/lemon juice. Remove bowl from mixer and stir with a spatula until everything is completely combined.
½ cup (120mL) fresh lemon juice2, ¾ cup (180mL) milk
Pour the batter evenly into the prepared pan and bake 28-32 minutes or until lightly browned on top and a toothpick or cake tester inserted in the center comes out clean. Remove from oven and allow cake to cool in the pan completely on a wire rack before removing and assembling.
LEMON BUTTERCREAM FROSTING
In a medium size bowl with a handheld mixer or in the bowl of stand mixer fitted with the paddle attachment, beat the butter and lemon zest on medium speed until smooth (about 3 minutes).
½ cup (113g) unsalted butter, zest of 1 lemon
Reduce the mixer to low, then slowly add the powdered sugar and mix until everything is combined. Add the vanilla extract and mix again.
2 cups (240g) powdered sugar, ½ teaspoon vanilla extract
Slowly add the lemon juice, watching for and stopping at desired consistency. Add the salt, then increase the mixer speed to medium and beat until completely smooth.
⅛ teaspoon salt, 2 to 3 Tablespoons (30-45mL) fresh lemon juice
ASSEMBLE CAKE
Spread the buttercream evenly over the top of the sheet cake (while it's still in the pan) with an offset spatula. Leftovers stay fresh, covered tightly, at room temperature up to 5 days and in the refrigerator up to 1 week.
Make ahead: prepare cake and frosting up to 1 day in advance. Cover cake tightly and keep at room temperature or in the refrigerator until ready to assemble. Refrigerate prepared frosting in an airtight container until ready to use. Unfrosted cake may be frozen, wrapped tightly, up to 2 months. Thaw overnight in the refrigerator before assembling. Frosted cake can be frozen, wrapped tightly, up to 2 months. Thaw overnight in the refrigerator and bring to room temperature before serving.
Video
Notes
Room temperature ingredients: these incorporate into batter much more easily than cold ingredients. Allow to sit at room temperature for 45 minutes. You can place eggs in a bowl of warm water for 10 minutes or until ready to use.
Lemon juice: you will need approximately 3 lemons for ½ cup of lemon juice. You can zest all 3 lemons, as you'll use the zest of 2 of them in the cake and 1 of them in the frosting.
Milk: a higher fat milk brings the best texture to this cake.
Nutrition Disclosure
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.