Decadent Oreo Sheet Cake with Creamy Oreo Frosting

If you love Oreos, this Oreo sheet cake deserves a spot on your baking list. A soft, moist chocolate cake studded with chopped Oreo cookies is topped with a light, fluffy cookies-and-cream buttercream—an easy, crowd-pleasing dessert perfect for birthdays, potlucks, holidays, or any day you need a show-stopping sweet.

Oreos have a way of turning ordinary desserts into something playful and nostalgic. In this sheet cake, a rich chocolate base, plenty of chopped cookies inside the batter, and a cookies-and-cream buttercream on top combine for a reliably delicious treat. Baked in a single 9×13-inch pan, this cake is simple to assemble and easy to share—no layering or complicated decorating needed.

Why You’ll Love This Oreo Sheet Cake

• Soft, moist chocolate cake with balanced cocoa flavor.
• Oreos in every bite from chopped cookies folded into the batter and mixed into the frosting.
• Easy to make—no layers, no fuss.
• Great for sharing—a 9×13 cake yields many servings for gatherings.
• Universal appeal—classic cookies-and-cream flavor kids and adults love.

Key Ingredients

• Oreo cookies – Regular Oreos work best; Double Stuf can change texture. Use roughly chopped cookies in the cake and a mix of finely and coarsely crushed cookies for the frosting.
• Unsweetened natural cocoa powder – Provides a rich chocolate flavor without overpowering the Oreos.
• Buttermilk – Keeps the crumb tender and adds a subtle tang to balance sweetness.
• Hot coffee or hot water – Blooms the cocoa for deeper chocolate notes; hot water is fine if you prefer no coffee flavor.
• Butter – Forms the base of the buttercream for a light, spreadable frosting that highlights the Oreo pieces.

How to Make Oreo Sheet Cake

Mix the dry ingredients.
Whisk together the flour, cocoa powder, baking powder, baking soda, and salt to ensure even distribution and to break up any lumps.

Combine the wet ingredients.
Whisk sugars, oil, eggs, and vanilla until smooth, then stir in the buttermilk. This is an oil-based cake, so there’s no need to cream butter or alternate dry and wet components.

Finish the batter.
Stir the dry ingredients into the wet until just combined, then slowly add the hot coffee or water. The batter will be thin—that’s normal and helps produce a moist, tender cake.

Fold in the Oreos.
Toss chopped Oreos with a tablespoon of flour so they stay evenly distributed, then fold them into the batter. Pour into a prepared 9×13 pan and spread evenly.

Bake until just done.
Bake 28 to 32 minutes at 350°F (175°C), or until a toothpick inserted in the center comes out with a few moist crumbs. Avoid over-baking to retain moisture. Cool the cake completely in the pan on a wire rack before frosting.

Make the cookies-and-cream buttercream.
Beat softened butter until creamy, then gradually mix in confectioners’ sugar. Add heavy cream, vanilla, and a pinch of salt, beating until light and spreadable. Fold in crushed Oreos—use some finely crushed crumbs for overall flavor and a few larger pieces for texture.

Frost and finish.
Spread the buttercream over the cooled cake with relaxed swoops for a rustic finish and sprinkle extra Oreo pieces on top if desired. Chill briefly to set the frosting if you prefer firmer slices.

Tips for Success

• Measure flour accurately. Too much flour dries the cake. Use a kitchen scale or the spoon-and-level method.
• Don’t over-mix. Stir just until the dry ingredients disappear to keep the cake tender.
• Chop the Oreos, don’t crush them for the batter. Larger pieces stay visible after baking and add that classic cookies-and-cream look.
• Cool completely before frosting. Warm cake can melt the buttercream and make the frosting thin.
• Mix cookie textures in the frosting. Finely crushed crumbs flavor every bite while larger pieces give satisfying texture.
• Finish with swoops. A relaxed, rustic top looks inviting and highlights the cookie pieces.

How to Store

Room temperature: Cover tightly and store up to 2 days.

Refrigerator: Tightly covered, store up to 4 days. Bring slices to room temperature for 20–30 minutes before serving for best texture.

Freezer: Wrap the whole cake or slices well and freeze up to 2 months. Thaw overnight in the refrigerator or for a few hours at room temperature.

Make ahead: The cake can be baked a day in advance. For the best frosting texture, frost the cake the day you plan to serve it; frosting a day ahead is fine but cookie pieces in the frosting will soften slightly over time.

One More Reason to Buy Oreos

If you’re baking for an Oreo lover, this sheet cake is hard to beat: easy to make, fun to serve, and reliably delicious. It’s a great option for celebrations or whenever you want a nostalgic, crowd-pleasing dessert. For more elaborate Oreo desserts, consider a layered cookies-and-cream cake that highlights the same flavors in a showier presentation.

Oreo Sheet Cake — Recipe Overview

Ingredients

For the cake:

• 1 ¾ cups (210 g) all-purpose flour, plus 1 tablespoon for the cookies
• ¾ cup (63 g) unsweetened natural cocoa powder
• 1 ½ teaspoons baking powder
• ½ teaspoon baking soda
• ¾ teaspoon salt
• 1 cup (200 g) granulated sugar
• ½ cup (100 g) firmly packed light brown sugar
• ½ cup (120 ml) vegetable oil or other neutral oil
• 2 large eggs, at room temperature
• 2 teaspoons vanilla extract
• ½ cup (120 ml) buttermilk, at room temperature
• ½ cup (120 ml) hot coffee or hot water (160–180°F)
• 14 Oreo cookies, roughly chopped

For the frosting:

• 1 cup (226 g) unsalted butter, softened
• 3 to 3 ½ cups (330–385 g) confectioners’ sugar
• 3 to 4 tablespoons (45–60 ml) heavy cream
• 2 teaspoons vanilla extract
• ¼ teaspoon salt
• 12 to 14 Oreo cookies, crushed (plus more for garnish)

Instructions

To make the cake:

1. Preheat the oven to 350°F (175°C). Grease a 9×13-inch pan and line with parchment if desired.
2. Whisk together flour, cocoa powder, baking powder, baking soda, and salt; set aside.
3. In a large bowl, whisk granulated sugar, brown sugar, oil, eggs, and vanilla until smooth. Whisk in the buttermilk.
4. Add the dry ingredients and mix until just combined.
5. Slowly stir in the hot coffee or water; the batter will be thin.
6. Toss chopped Oreos with 1 tablespoon flour, then fold into the batter.
7. Pour batter into the prepared pan and spread evenly.
8. Bake 28–32 minutes, or until a tester comes out with a few moist crumbs attached.
9. Cool the cake completely on a wire rack before frosting.

To make the frosting:

1. Beat the softened butter on medium speed until creamy.
2. Gradually add 3 cups (330 g) confectioners’ sugar and mix until smooth.
3. Add 3 tablespoons (45 ml) cream, vanilla, and salt; beat until fluffy. Adjust with more sugar or cream for desired consistency.
4. Fold in the crushed Oreos, using both finely crushed and some larger pieces for texture.
5. Spread the frosting over the cooled cake and sprinkle extra cookie pieces if desired.

Notes

• Regular Oreos work best; Double Stuf can alter texture.
• Hot coffee enhances chocolate flavor without making the cake taste like coffee; hot water is an acceptable substitute.
• The batter will be thin after adding hot liquid—that’s normal and yields a tender cake.
• For best texture, enjoy within the first couple of days; frosting cookie pieces will soften over time but still taste great.
• Makes about 15 generous servings; cut smaller to increase portions.

Author: Jennifer McHenry