Desserts
This copycat Costco sheet cake recipe delivers the same triple-layered vanilla perfection with buttery frosting you love from the store—now made perfectly at home. The secret lies in a precise balance of ingredients and gentle folding techniques that create that signature light, airy texture.
My version has become the go-to for parties, potlucks, and special occasions because it consistently delivers restaurant-quality results.
What sets this recipe apart is the foolproof method for achieving fluffy layers and smooth frosting without professional equipment. You'll work with simple pantry staples but follow professional techniques like creaming butter and sugar properly and folding dry ingredients just until combined.
The buttercream frosting is rich yet light, with the perfect balance of sweetness that makes every slice irresistible.
By the time you're done, you'll have a cake that looks and tastes exactly like the Costco version—moist vanilla layers separated by velvety buttercream, all baked to golden perfection. The frosting spreads smoothly and holds its shape beautifully, making it perfect for decorating or serving as-is.
This recipe serves 12-15, making it ideal for gatherings where you want to impress without the stress.
Pro tip: Let the cake cool completely before frosting to ensure clean layers and professional results. The frosting can be made ahead and chilled until ready to use, saving you time during the final assembly.
Whether you're celebrating a birthday or just treating yourself, this copycat version delivers the same crowd-pleasing quality you expect from Costco—now with the satisfaction of making it yourself.
Ingredients for copycat costco sheet cake
Sixteen ingredients for fifteen servings of Costco-worthy sheet cake perfection.
| Ingredient | Amount | Notes |
|---|---|---|
| All-Purpose Flour 🌾 | 6 cups | Sifted for light texture |
| Granulated Sugar 🍚 | 2 ¼ cups | Superfine preferred for smoothness |
| Unsalted Butter 🧈 | 1 ½ cups | Cold, cubed for creaming |
| Large Eggs 🥚 | 6 whole | Room temperature for best mixing |
| Vanilla Extract 🌸 | 2 tbsp | Pure, high-quality extract |
| Baking Powder 🍞 | 2 tbsp | Freshly opened for lift |
| Salt 🧂 | ½ tsp | Fine sea salt preferred |
| Milk 🥛 | 1 ½ cups | Room temperature for smooth batter |
| Buttercream Frosting 🧁 | 4 cups | Homemade or store-bought (see notes) |
| Powdered Sugar 🍚 | 8 cups | Sifted for smooth frosting |
| Heavy Whipping Cream 🥛 | 2 cups | Cold, for stable frosting |
| Vanilla Bean Paste 🌸 | 1 tbsp | For deeper vanilla flavor |
| Cornstarch 🌾 | 1 tbsp | For frosting stability |
The flour and butter are your foundation. King Arthur or Gold Medal flour gives the best texture—avoid self-rising. For the butter, Plugrá or Land O'Lakes unsalted are my go-tos, but any cold, high-fat butter works. The secret to that signature Costco texture? Don't overmix—fold just until combined. I always measure my flour by weight (375g for 6 cups) if I have a scale, but if you're using cups, spoon it in and level off. The vanilla extract matters too—Nielsen-Massey or McCormick pure extract makes a noticeable difference over imitation.
No vanilla bean paste? Double the vanilla extract—it won't be identical, but it'll still taste amazing. For the frosting, I make mine from scratch because store-bought never quite captures that velvety texture, but Betty Crocker or Duncan Hines buttercream in a box works in a pinch (just add extra milk to thin it). The heavy whipping cream should be very cold—store it in the freezer for 15 minutes before whipping. For the powdered sugar, Domino or C&H work perfectly, but avoid anything with anti-caking agents if you can. Pro tip: Sift both your flour and powdered sugar to avoid lumps in the frosting.
This cake keeps beautifully—covered at room temp for 2 days or fridge for 5 days. The frosting? Up to 1 week refrigerated, but bring it to room temp before spreading. I always make a double batch of frosting and freeze half in a sealed container for next time. The cake layers can be wrapped individually and frozen for up to 3 months—just thaw overnight before frosting. For serving, use a serrated knife dipped in hot water for clean slices. Trust me, your guests will never guess it's homemade.
Why You'll Love This Recipe
- Sheet Pan Magic: I swear by this recipe because it’s one bowl—just flour, sugar, butter, eggs, and vanilla. No mixer, no fuss, just stir until smooth and bake. The kind of recipe that makes me feel like I’ve earned my dessert without actually doing much.
- Butter-Sugar Bliss: That rich, buttery flavor? It’s the secret. The melted butter and sugar caramelize just enough to give it that Costco-level tender crumb and a golden crust that cracks perfectly. Honestly, I’ve tried store-bought—this tastes better, and I’m not even kidding.
- Party in a Pan: This cake is my go-to for birthdays, potlucks, or just because. Cut it into squares, layer it with whipped cream, or serve it plain—it’s always a hit. (Yes, even on a Tuesday night.) Plus, it feeds a crowd without the stress of individual cakes.
- Budget Baking Win: For under $10, I get a full sheet cake that lasts days. The leftovers? Perfect for breakfast toast or a quick snack. And since it’s just pantry staples, I never feel guilty about baking it again and again—no weird ingredients to track down.
Step-by-step instructions for triple-layered vanilla sheet cake
Here's how to recreate that iconic Costco sheet cake at home—moist layers and velvety frosting every time.
Prepare the Cake Layers
Preheat your oven to 350°F and grease three 9x13-inch baking pans with butter or line them with parchment paper. Sift together the 6 cups all-purpose flour, 2.25 cups granulated sugar, 2 tbsp baking powder, and 0.5 tsp salt in a large bowl. I always sift the dry ingredients first to prevent lumps in the batter.
In a separate bowl, beat the 1.5 cups unsalted butter (cold, cubed) with the 6 whole large eggs (room temperature) on medium speed until light and fluffy—about 3-4 minutes. Gradually add the dry mixture while mixing on low speed, alternating with the 1.5 cups milk. Finish by mixing in the 2 tbsp vanilla extract until just combined. The batter should be smooth but slightly thick.
Divide the batter evenly among the prepared pans. Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean. Let the layers cool in the pans for 10 minutes before transferring to a wire rack to cool completely. This gradual cooling prevents cracking when stacking later.
Prepare the Buttercream Frosting
In a stand mixer fitted with the paddle attachment, beat the 2 cups heavy whipping cream (cold) on medium speed until soft peaks form. Gradually add the 8 cups powdered sugar while mixing on low speed, then increase to medium-high until smooth and fluffy—about 2-3 minutes. Add the 1 tbsp vanilla bean paste and 1 tbsp cornstarch for stability and deeper flavor.
In a separate bowl, beat the 4 cups buttercream frosting (store-bought or homemade) until smooth. I like to warm the store-bought frosting slightly in the microwave for 10-15 seconds to make it easier to incorporate. Gradually fold the whipped cream mixture into the buttercream until fully combined and smooth. This creates a lighter, more stable frosting that won't melt too quickly.
Assemble the Triple-Layered Cake
Place the first cake layer on a serving tray or cake stand. Spread a thin layer of frosting (about ¼ cup) over the top to create a "crumb coat." This helps prevent crumbs from getting into the final frosting layer. Repeat with the second and third layers, stacking them carefully and leveling each one with a serrated knife if needed.
Spread the remaining frosting evenly over the top and sides of the cake, using an offset spatula for a smooth finish. I like to create a slight overhang on the sides for that classic Costco look. Chill the cake in the refrigerator for 30 minutes before serving to help the frosting set slightly. This step ensures clean slices and prevents the frosting from sliding off.
Final Touches and Serving
Once chilled, use a serrated knife to trim any uneven edges and create clean sides. For that signature Costco presentation, I like to dust the top lightly with additional powdered sugar using a fine-mesh sieve. This adds a decorative touch while keeping the cake looking fresh.
Slice into 15 equal portions (about 2x2-inch squares) and serve immediately. The cake should have a tender crumb with a slight springiness, while the frosting remains smooth and buttery. If the frosting starts to soften in warm rooms, simply chill the cake for 10-15 minutes before serving again.
Pro Tips For Making Copycat Costco Sheet Cake
- Cream Butter Properly: I learned this the hard way—softened butter mixed with sugar should take 3-5 minutes in a stand mixer on medium. Stop when it’s light and fluffy, not pale yellow. If you rush, the cake turns dense instead of tender.
- Sift the Flour Twice: This recipe relies on air for that signature lightness. Sift the flour before adding it to the butter-sugar mix, then sift it again when folding it in. Yes, it’s extra work, but it’s the thing that keeps the texture buttery and airy—not heavy.
- Don’t Overmix the Batter: Once you start adding the flour, mix just until combined—maybe 10-12 strokes. Overmixing develops gluten, and that’s how you end up with a cake that’s more like a dense brownie. Stop when there are no more streaks of flour.
- Bake Until Cool to Touch: The Costco version has that perfect set—firm but still warm. Bake until the edges pull away just slightly and the center springs back when pressed. If you pull it out too soon, it’ll collapse. If you wait too long, it’ll dry out. Aim for 25-30 minutes at 350°F.
Serving suggestions for this recipe
Party Presentation
For gatherings, slice the cake into 2x2-inch squares using a serrated knife dipped in hot water—this ensures clean cuts every time. Arrange slices on a large platter with a dusting of powdered sugar for that bakery-fresh look.
I love adding fresh berries (strawberries or raspberries) along the edges for a pop of color and freshness. 🍓
Individual Servings
When serving smaller groups, wrap individual slices in parchment paper or clear cellophane with a ribbon for a gift-like presentation. Add a miniature flag or personalized label for birthdays or celebrations. I often use baker's twine to tie the packages for a rustic touch that still feels elegant.
Frosting Variations
For a festive twist, tint the frosting with gel food coloring—gold for autumn, red for holidays, or pastel pink for spring. Swirl the colored frosting into the base layer before adding the final white coating for a marbled effect.
A sprinkle of edible glitter on top adds extra sparkle for special occasions. 💫
Serving Temperature
This cake is best served at room temperature for the perfect balance of texture. If your kitchen is warm, chill the cake for 10-15 minutes before slicing to keep the frosting firm.
For outdoor events, place the cake in a cooling rack under a shade tent to prevent melting. I always bring a small insulated cake carrier when transporting to ensure it stays fresh.
Pairing Ideas
Serve with vanilla ice cream or whipped cream for a decadent dessert duo. A cup of coffee or hot chocolate complements the cake beautifully, especially during colder months. For a refreshing contrast, offer sparkling lemonade or iced tea to cleanse the palate between bites. 🍦
Make-Ahead Serving
Assemble the cake one day ahead and store it in an airtight container at room temperature. Refrigerate for up to 24 hours if your kitchen is warm. Bring it to room temperature before serving to restore the perfect texture.
I always make the frosting a day ahead and store it in the fridge for easier assembly on the big day. ⏰
Nutrition facts
Frequently asked questions
Why does the Costco sheet cake have three layers?
The triple-layered design creates a perfect balance of texture and portion size. Each layer stays moist longer, and the frosting between them adds richness without overwhelming the vanilla flavor. This structure also makes it easier to slice cleanly for serving—ideal for large gatherings where you want consistent portions.
Can I make this cake in a single 9x13-inch pan instead of three?
No, this recipe requires three separate layers to achieve the signature texture and height. A single-layer cake would be too dense and lack the signature fluffiness. The thin layers also ensure even baking and cooling. If you're short on pans, bake two layers at a time and let them cool completely before frosting.
What's the secret to getting the frosting as smooth as Costco's?
The key is using cold heavy whipping cream and folding it gently into the buttercream. Chill the frosting for 30 minutes before spreading, and use a paddle attachment on low speed when mixing. For extra smoothness, sift the powdered sugar and avoid overmixing. A cornstarch slurry (1 tbsp cornstarch + 1 tsp water) can also help stabilize it.
How do I store leftovers without the cake getting soggy?
Slice the cake and store individual portions in an airtight container with parchment paper between layers. Keep it at room temperature for 2 days or refrigerate for 5 days. For longer storage, freeze slices wrapped tightly in plastic for up to 3 months. Always bring refrigerated cake to room temperature before serving.
Can I substitute the buttercream frosting with cream cheese frosting?
While possible, it won't match the signature Costco texture. Buttercream provides a lighter, more stable base that pairs perfectly with the vanilla cake. If you must use cream cheese frosting, reduce the sugar slightly and add 1 extra tbsp of cornstarch to prevent graininess. The flavor will be different, but it can still work for special occasions.