- As someone who gave up their Costco membership after moving to NYC, I was beyond excited when one of our food editors created a copycat Costco sheet cake recipe.
- I followed her lead with a doctored cake mix, vanilla cheesecake mousse, and a nostalgic frosting made with shortening—and it truly tastes just like the original.
- It cost me less than $25 to make, took less time than a warehouse run, and let me decorate it exactly how I wanted.
The worst part about living alone in New York is that I can’t justify renewing my Costco membership. I’m green with envy every time I see people in the suburbs sharing their warehouse hauls. As much as I want to indulge in a huge tray of mac-and-cheese and six pounds of peanut butter, I’ve accepted my fate as an outside observer. But there are still days when I yearn for a Costco treat.
So when our very own Taylor Ann Spencer took on the task of developing a copycat Costco sheet cake, I nearly jumped for joy. The massive rectangular cake was a fixture at every childhood birthday party, complete with mounds of decorative frosting. It’s fluffy, sweet, and everything you could possibly want in a dessert.
Costco stays tight-lipped about its recipes, but Taylor Ann managed to crack the code. Her version is a dead-ringer for the real thing. Now I can finally celebrate birthdays in style—even without a membership card.
What Makes Copycat Costco Sheet Cake So Special
Aside from the obvious benefits for non-Costco members, there are plenty of pros to making your own sheet cake. Baking your own cake allows for more customization than you’re able to get at the warehouse. Whether you want to throw chocolate chips in the batter or add fresh fruit between the cake layers, you really have the freedom to design your dream cake.
On top of that, it also takes much less time than you’d expect. Ordering a custom cake at Costco usually requires at least 24 hours’ notice. But you can make your own cake at home in less time than it takes to navigate the warehouse on a Saturday afternoon.
And, despite Costco’s steep discounts, the homemade version costs roughly the same as store-bought. Aside from a few baking essentials in your pantry, you only need a few extra ingredients to put it all together. I’ve done the math with New York City grocery prices—and I can make my own sheet cake for less than $24.99 (and I can skip the $65 annual membership fee!).
How To Make Copycat Costco Sheet Cake
The cake itself begins with a boxed cake mix. But instead of following the package instructions, we doctor it with egg whites, sour cream, milk, oil, and vanilla. Once the cake batter is combined, we divide it between two greased and parchment-lined baking pans and pop them in the oven for 20 to 25 minutes.
From there, we move on to the vanilla cheesecake mousse that’s used for the center layer. We start by combining a softened block of cream cheese, confectioners’ sugar, and salt in a stand mixer. Once it’s smooth, we add in milk and a package of instant vanilla pudding (our second shortcut!). The pudding does double duty by providing both flavor and structure to the mousse. The last step involves adding heavy cream until the whole thing is thick and fluffy.
At this point, our cakes are ready to start assembly. We place one of the baked, cooled, and trimmed cakes on a platter. Then, we spread all of our vanilla cheesecake mousse across the top in an even layer before placing our second cake on top. That can sit in the fridge while we prepare the final component: Costco’s famous frosting.
Some of the best frostings start with lots of butter, which is how Taylor Ann originally approached this recipe. But after several rounds of testing, we discovered that the secret to achieving the perfect frosting is using vegetable shortening instead! It has a more authentic Costco flavor, it’s cheaper than butter, and you don’t have to wait for the shortening to soften. It’s a win-win all around.
We start by beating the shortening in a stand mixer, along with water, vanilla, and salt. The second and final step is adding the confectioners’ sugar—a whole 8 cups. Before you panic, remember that this cake feeds a lot of people. And you’re probably making this for a special occasion, so you deserve to enjoy something sweet anyway.
Now that our frosting is ready, it’s time to complete the cake by spreading frosting across the tops and sides of the cake (don’t forget to save some for piping!). Our final step is to get creative with the decorations. Pipe a fun border! Add some cute designs! Dust the top with a mountain of sprinkles! The world is your oyster—so feel free to make it as simple or elaborate as you’d like.
My Tips For Making A Copycat Costco Sheet Cake
- Bake the cakes ahead of time. This dessert is best enjoyed soon after it’s fully frosted, but you can make some of the components in advance. I like baking the cakes the day before, wrapping them in plastic wrap, and finishing the assembly once I’m ready to enjoy.
- Get creative with the decorations. This recipe is the perfect blank canvas for whatever flavorful flourishes you like. I think fresh berries are a great addition, especially if you arrange them in a cool pattern.
