Fudgy Brownie Cake

Slice of brownie cake topped with chocolate frosting and rainbow sprinkles.

If you’ve ever wished that brownies could be just a little more celebratory, this brownie cake is the answer. Baked in a round cake pan and finished with a thick layer of creamy chocolate frosting, it strikes the perfect balance of fudgy brownies with all the nostalgia of a classic chocolate cake.

Course Dessert

Cuisine American

Prep Time 25

Cook Time 32

Total Time 57

Servings

Calories 504kcal

Author Allison Mattina

Ingredients

Brownie cake:

10 tablespoons (142g) unsalted butter cut into ten pieces
1½ cups (300g) light brown sugar lightly packed
¾ cup (63g) unsweetened cocoa powder
1 cup (125g) all purpose flour spooned and leveled
1 tablespoon cornstarch
¼ teaspoon baking soda
¼ teaspoon salt
2 tablespoons vegetable or canola oil
3 large eggs
1½ teaspoons pure vanilla extract
⅔ cup (120g) semisweet chocolate chips

Chocolate frosting:

½ cup (113g) unsalted butter softened
⅓ cup (35g) unsweetened cocoa powder
2⅓ cups (280g) powdered sugar
2-3 tablespoons milk
½ teaspoon pure vanilla extract

Instructions

Brownie cake:

Preheat oven to 350°F. Line 9-inch round springform pan or round cake pan with parchment paper (don't skip this step). See note about pan size, especially if using a cake pan. Grease the pan well. Set aside.
Place butter and brown sugar in a large microwave safe bowl. Microwave in 20 second increments, stirring between each, until the butter is completely melted. This took about 1 minute. Stir the mixture well, some of the brown sugar will begin to dissolve but not all of it. Set aside to cool for 5 minutes. Meanwhile, proceed with the dry ingredients.
In a separate bowl, combine cocoa powder, flour, cornstarch, baking soda, and salt. Whisk the mixture to break up any lumps. Set aside.
Whisk oil into the melted butter/sugar. Then whisk in eggs followed by vanilla. Sprinkle the dry ingredients over the wet ingredients and whisk until just a few streaks of flour remain. Tap the excess batter off the whisk and remove the whisk from the bowl. Add the chocolate chips and stir with a silicone spatula until completely combined, scraping the sides and the bottom of the bowl as needed.
Add the batter to the prepared pan and smooth into an even layer. Bake for 32-38 minutes. The brownies should be removed from the oven when a toothpick inserted into the brownies come out with moist fudgy crumbs on it (no thin raw batter). Remember, there are chocolate chips in there, so melted chocolate is ok. Place the pan on a wire rack to cool completely.

Chocolate frosting:

Using a hand mixer or stand mixer fitted with the paddle attachment, beat butter until smooth. Add half the powdered sugar and all the cocoa powder. Beat in vanilla and 2 tablespoons milk followed by remaining powdered sugar. Add more milk, as needed, to get your desired consistency. Turn speed up to medium-high and beat for 30 seconds.
Remove the brownie from the pan and place on a serving plate. Note: if using a cake pan it helps to run a thin, sharp knife around the edges of the pan before turning it out onto a plate. Spread an even layer of frosting over the top of the brownie and top with sprinkles.

Notes

Pan options

9-inch round cake pan: A traditional 9-inch round cake pan can be used but it MUST have 2-inch high sides (I use this pan affiliate link). If your 9-inch round pan is shallow the batter will likely overflow. Be sure to grease your pan really well and line the bottom with parchment. After the brownie has cooled completely, run a thin sharp knife around the edges of the pan to help release the brownie, then turn it out onto a plate.

9-inch round springform pan: This option allows you to remove the sides of the pan from the brownie, rather than remove the brownie from the pan. If you use a springform pan be sure it has a tight seal so no batter leaks out. You can also wrap the bottom of the pan with a thin layer of foil to ensure no leaks occur.

Serving and storage

Serve at room temperature for the best texture. Store in the refrigerator for up to 3 days.

Nutrition