For this Sheet Pan Birthday Cake, I combined two recipes: one, Ina Garten’s Birthday Sheet Cake Recipe on foodtv.com, and the other, a frosting, from Magnolia Bakery. Then I added just the right amount of food coloring to make it purple, and decorated with sprinkles and M&Ms!
The cake is a great way to serve a big crowd!
Sheet Pan Birthday Cake
18 tablespoons (2 1/4 sticks) unsalted butter, at room temperature
3 cups sugar
6 extra-large eggs, at room temperature
8 ounces (about 1 cup) sour cream, at room temperature
1 1/2 teaspoons pure vanilla extract
1 lemon, zested
3 cups all-purpose flour
1/3 cup cornstarch
1 teaspoon kosher salt
1 teaspoon baking soda
Preheat the oven to 350 degrees F. Butter and flour a 12 by 18 by 1 1/2-inch sheet pan.
To make the cake, cream the butter and sugar on medium-high speed in the bowl of an electric mixer fitted with a paddle attachment until light and fluffy, about 5 minutes. On medium speed, add the eggs, 2 at a time, then the sour cream, vanilla, and lemon zest, scraping down the bowl as needed. Mix well. Sift together the flour, cornstarch, salt, and baking soda. With the mixer on low speed, slowly add the flour mixture to the butter mixture and stir just until smooth. Finish mixing by hand to be sure the batter is well mixed. Pour evenly into the pan, smooth the top with a spatula, and bake in the center of the oven for 25 to 30 minutes, or until a toothpick comes out clean. Cool in the pan to room temperature.
Magnolia Bakery Icing
1 cup unsalted butter, very soft
8 cups confectioners’ sugar
1⁄2 cup milk
2 teaspoons vanilla
place the butter in a large mixing bowl.
Add 4 cups of the sugar and then the milk and vanilla.
Beat until smooth and creamy.
Gradually add the remaining sugar, 1 cup at a time, until icing is thick enough to be of good spreading consistency (you may very well not need all of the sugar).
If desired, add a few drops of food coloring and mix thoroughly.
Use and store icing at room temperature, as icing will set if chilled.
Can store in an airtight container for up to three days.
