Introduction

This Brownie Oreo Cake is a delightful combination of rich, fudgy brownies and moist Oreo-studded cake layers, all wrapped in creamy Oreo buttercream frosting. Perfect for celebrations or any time you want to impress with a decadent dessert that’s sure to please a crowd.

The image shows a tall, round cake with four thick layers on a white cake stand. The outer frosting is light brown with small dark cookie crumbs mixed in, and a smooth chocolate drip glaze falls down from the top edge. The top is decorated with swirls of the light brown frosting, alternating with whole dark chocolate sandwich cookies and chunks of brownie. In front of the cake, a white plate holds a large slice showing alternating layers of light vanilla cake with cookie bits and rich dark chocolate filling. The slice is garnished with extra sandwich cookies, a dollop of frosting, and a brownie piece. The whole scene is set on a white marbled surface. Photo taken with an iphone --ar 4:5 --v 7

Ingredients

3 cups all-purpose flour (375g)
3 cups granulated sugar (600g)

2 1/2 tsp baking powder (10g)
1 tsp fine salt (6g)

1 cup (2 sticks) unsalted butter, room temperature (226g)
1 cup carton egg whites or 7 large egg whites, room temperature (235g)

1 1/2 cups buttermilk, room temperature (345g)
2 Tbsp vegetable or canola oil (28g)
2 tsp vanilla extract or vanilla bean paste (8g)

1 cup chopped Oreos – about 9 Oreos (75g)
4 1/2 cups granulated sugar (900g)
2 1/4 cups all-purpose flour (280g)

2 cups unsweetened baking cocoa (160g)
1 1/2 cups powdered sugar (190g)
1 1/2 cups milk or dark chocolate chips (255g)

2 tsp fine salt (12g)
6 large eggs, room temperature (336g)
1 1/2 cups vegetable or canola oil (340g)

1/3 cup water (80g)
1 Tbsp vanilla extract or vanilla bean paste (12g)
3 cups unsalted butter, room temperature (678g)

1 Tbsp vanilla extract or vanilla bean paste (12g) for frosting
1 tsp fine salt (6g) for frosting
11 cups powdered sugar (1375g)

1/2 cup heavy whipping cream, room temperature (120g)
1 cup finely crushed Oreo crumbs – about 12 Oreos (100g)

Instructions

Step 1: Preheat the oven to 350°F (175°C). Line three 8-inch cake pans with parchment circles and grease with non-stick spray for the Oreo cake layers.

Step 2: In a large bowl or stand mixer, whisk together 3 cups flour, 3 cups sugar, baking powder, and salt until combined.
Step 3: Slowly add 1 cup room temperature butter to the dry ingredients on low speed. Mix until the texture resembles moist sand with no large butter chunks.
Step 4: Add 1 cup egg whites and mix on low until just combined. Then add buttermilk in two parts, mixing gently after each addition.

Step 5: Mix in vegetable oil and vanilla extract. Scrape the bowl sides, then beat on medium speed for about 30 seconds for even mixing.
Step 6: Fold in chopped Oreos gently, then divide the batter evenly into the prepared cake pans. Bake for 34-36 minutes, or until a toothpick inserted comes out with a few moist crumbs.
Step 7: Let cakes cool 10 minutes in pans, then run an offset spatula along the edges to loosen. Freeze layers for 30 minutes to cool fully, then remove and level the tops with a serrated knife.

Step 8: Prepare brownie layers by lining and greasing two round 8-inch pans and one square 8-inch pan. Keep the oven at 350°F (175°C).
Step 9: In a large bowl, whisk together sugar, flour, cocoa, powdered sugar, chocolate chips, and salt.
Step 10: In another bowl, whisk eggs, vegetable oil, water, and vanilla extract. Combine wet and dry ingredients and stir just until combined.

Step 11: Divide brownie batter evenly among the prepared pans (about 830g per pan). Bake for 43-53 minutes; round pans take longer than the square pan.
Step 12: Cool brownies on wire racks. Run an offset spatula around edges while warm to loosen them from the pans.
Step 13: For Oreo buttercream, beat 3 cups butter on medium speed until smooth. Add vanilla and salt, then slowly add powdered sugar, alternating with heavy cream to reach desired consistency.

Step 14: Fold in crushed Oreo crumbs evenly. Cover and set aside until ready to assemble.
Step 15: Assemble cake by stacking alternating Oreo cake layers and brownie layers on a cake board with frosting between each layer.
Step 16: Apply a thin crumb coat of frosting around the assembled cake, smooth with a bench scraper, and chill until firm (30 minutes in fridge or 10 minutes in freezer).

Step 17: Apply a second thick layer of frosting and smooth again. Decorate top with buttercream swirls, remaining cut brownies, and Oreos as desired.
Step 18: Use a sharp warm knife to slice for clean cuts and enjoy your indulgent Brownie Oreo Cake!

Tips & Variations

Use a kitchen scale to evenly divide batter for uniformly sized cake layers and even baking.

Freeze cake layers after baking to speed cooling and make assembly easier.
Adjust frosting thickness with additional cream or powdered sugar to suit spreading or piping needs.
Decorate with chocolate ganache drip for an extra touch of decadence.

For a lighter cake, substitute half the oil in the brownie batter with applesauce.

Storage

Store the assembled cake in an airtight container or covered in the refrigerator for up to 5 days. Before serving, allow the cake to come to room temperature for about 30 minutes. You can freeze the cake layers or the whole cake wrapped tightly in plastic wrap and foil for up to 3 months; thaw overnight in the refrigerator before serving.

How to Serve

A tall, layered cake with three light cream-colored layers speckled with dark cookie bits, alternating with two rich dark chocolate layers in between, sits on a white cake stand. The cake is covered evenly with light cookies and cream frosting, and the top edge is decorated with smooth chocolate ganache dripping down the sides. On top, there are six swirls of cookies and cream frosting, each holding a half Oreo cookie and a piece of brownie. A large slice of this cake is placed on a white plate, showing the clear layers, and is garnished with extra whole Oreos, a swirl of frosting, and a brownie piece beside it. The setting is a clean kitchen counter with a white marbled texture. photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use whole eggs instead of egg whites in the cake layers?

Using whole eggs will change the texture and moisture of the cake. Egg whites keep the cake lighter and less dense, which complements the rich brownie layers. If you use whole eggs, expect a slightly denser cake.

How do I keep the brownies moist and fudgy in the cake?

Be careful not to overbake the brownies; check them at the minimum baking time by inserting a toothpick. It should come out with moist crumbs, not dry. Also, use room temperature ingredients for better mixing and moisture retention.