One-Bowl Fudgy Chocolate Brownie Cake

If a rich, fudgy brownie and a slice of chocolate cake had a baby, you’d get this Chocolate Brownie Cake. It comes together in one bowl while the oven heats up, and the center stays almost molten.

The hardest part is waiting for it to cool enough to slice, but once you do, you get a dense, fudgy slice that needs nothing more than a dusting of powdered sugar.

Why This Brownie Cake Works

The batter is forgiving because you melt the butter and stir everything by hand. No mixer, no creaming, just a whisk and a spatula.

A thin, shiny crust forms on top while the inside bakes into a deeply chocolatey, slightly gooey layer. The pockets of melted chocolate chips keep every bite fudgy, and the cake stays moist for days.

Ingredients

• 1 cup unsalted butter: melted; use real butter for the best flavor and crackly top
• 1 1/2 cups granulated sugar: dissolves into the warm butter and creates that shiny crust
• 3/4 cup light brown sugar, packed: adds chew and a hint of caramel
• 1 cup unsweetened cocoa powder: natural or Dutch-process both work, but natural gives a slightly fruitier depth
• 1/2 teaspoon fine sea salt: brings all the chocolate forward
• 3 large eggs, at room temperature: cold eggs can make the batter seize, so pull them out early
• 1 teaspoon vanilla extract: rounds out the sweetness
• 1/2 cup all-purpose flour: just enough to hold things together, keeping the cake dense
• 1 cup semisweet chocolate chips: extra pockets of melted chocolate; swap for milk or dark if you prefer
• 1/2 teaspoon espresso powder, optional: doesn’t make it taste like coffee, just deepens the chocolate

Variations / Substitutions

• Use white chocolate chips: gives a creamy, extra-sweet contrast to the dark cocoa
• Swap 1/2 cup of the chips for toasted walnuts or pecans: adds crunch and a nutty toastiness
• Make it gluten-free: use a 1:1 gluten-free flour blend in place of the all-purpose flour
• Dutch-process cocoa: produces a darker cake with a smoother, less sharp chocolate note
• Add 1/2 teaspoon cinnamon or a pinch of cayenne: warms up the chocolate without overpowering

If you love this one, try the Classic Chocolate Layer Cake.

How To Make Chocolate Brownie Cake

Step 1: Melt the Butter and Whisk the Sugars

Heat your oven to 350°F (180°C). Line an 8-inch square baking pan with parchment paper, leaving a bit of overhang on the sides so you can lift the cake out later.

In a large bowl, melt the 1 cup butter in the microwave or over a double boiler. While it’s still warm, whisk in the 1 1/2 cups granulated sugar and 3/4 cup brown sugar. Keep whisking until the mixture is smooth and the sugars start to dissolve, about 1 minute. You’ll see the batter turn glossy and a deep caramel color.

Let the bowl sit for a minute off the heat before you add the eggs. A quick cool-down keeps them from scrambling when they hit the warm butter.

Step 2: Beat in the Eggs and Vanilla

Crack the 3 large eggs into the bowl one at a time. Beat each one in with a whisk before adding the next. Pour in the 1 teaspoon vanilla extract at the same time.

Whisk everything until the batter thickens and lightens just a shade, about 1 minute. It should look smooth and fudgy, with no streaks of egg white. This step builds the structure that gives the cake its dense, brownie-like texture.

Stop whisking as soon as it’s all mixed. Overbeating at this point can introduce too much air.

Step 3: Sift the Cocoa and Flour Into the Batter

Place a fine-mesh sieve over the bowl and sift the 1 cup cocoa powder, 1/2 cup flour, and 1/2 teaspoon salt right onto the wet mixture. Sifting breaks up any lumps so you don’t have to stir as much later.

Now fold with a spatula just until no dry streaks remain. The batter will be thick, almost like a stiff chocolate pudding. Resist the urge to overmix. Stir until the last few floury patches blend in, then stop.

Overworking the batter will make the cake tough instead of fudgy, so treat it gently.

Step 4: Fold in the Chocolate Chips

Scatter the 1 cup chocolate chips over the top of the batter. Fold them in with the spatula, working from the bottom of the bowl upward to distribute them evenly.

Scrape the batter into your prepared pan and smooth the top with the spatula. Give the pan a couple of firm taps on the counter. This settles the batter and releases any large air pockets that could create holes in the cake.

Step 5: Bake the Cake

Slide the pan into the preheated oven and bake for 30 to 35 minutes. At the 30-minute mark, test with a toothpick poked into the center. You want it to come out with a few moist crumbs clinging to it. A clean toothpick means you’ve overbaked.

The top will develop a thin, crackly crust and the edges will have puffed slightly higher than the center. The cake will look underdone in the middle, and that’s exactly right. It will set up as it cools.

Let the cake cool in the pan on a wire rack for at least 1 hour. If you slice it while it’s hot, it will crumble.

Step 6: Slice and Dust with Powdered Sugar

Once the cake is completely cool, grab the parchment overhang and lift the whole thing out of the pan. Place it on a cutting board. Use a sharp chef’s knife to slice it into 9 squares, wiping the blade clean between cuts for neat edges.

Dust the top generously with powdered sugar or a light snowfall of cocoa powder. Serve at room temperature, or pop a square into the microwave for 10 seconds if you want the chips to melt again.

A Few Tips for the Browniest Cake

• Use room-temperature eggs. Cold eggs can make the batter stiffen up when they hit the warm butter, and you’ll lose that glossy texture.
• Pull the cake when the center still wobbles just slightly. The carryover heat will finish it outside the oven, leaving you with a fudgy middle instead of a dry one.
• For the cleanest cuts, chill the cooled cake in the fridge for 15 minutes before slicing. The chocolate firms up and doesn’t drag through the knife.
• If you only have a 9-inch square pan, drop the bake time to 25 to 30 minutes and expect a slightly thinner cake.
• Store any leftovers with a slice of bread in the container. The bread will dry out while the cake stays moist.

Bake times by pan size:

Storing Leftover Brownie Cake

• Refrigerate: Keep in an airtight container at room temperature for up to 3 days, or in the fridge for up to a week.
• Reheating: Microwave a square for 15 to 20 seconds to get the chips gooey again, or warm the whole slab in a low oven for a few minutes.
• Serve Cold: Chilled brownie cake tastes almost like fudge. It’s dense and sliceable straight from the fridge.

Frequently Asked Questions

Can I use Dutch-process cocoa instead of natural?

Yes. Dutch-process gives a darker, smoother flavor. The cake will still be fudgy, just less sharp.

Can I make this cake gluten-free?

Absolutely. Replace the all-purpose flour with an equal amount of a 1:1 gluten-free flour blend. The texture stays dense.

Can I leave out the chocolate chips?

You can, but the chips add pockets of melted chocolate that make each bite extra fudgy. Substitute an equal amount of chopped nuts or just leave them out for a plain brownie cake.

Why did my cake turn out dry?

Usually overbaking is the culprit. Pull it when a toothpick has moist crumbs, not clean. Also, make sure you measured the flour correctly. Scooping straight from the bag packs in too much.

Chocolate Brownie Cake Recipe

Print Recipe Pin Recipe

Prep Time 10 minutes mins

Cook Time 35 minutes mins

Total Time 45 minutes mins

Servings: 9 servings

Calories: 534

Ingredients Method Notes

Ingredients

  

• 1 cup unsalted butter
• 1 1/2 cups granulated sugar
• 3/4 cup light brown sugar, packed
• 1 cup unsweetened cocoa powder
• 1/2 teaspoon fine sea salt
• 3 large eggs, at room temperature
• 1 teaspoon vanilla extract
• 1/2 cup all-purpose flour
• 1 cup semisweet chocolate chips
• 1/2 teaspoon espresso powder, optional

Method

 

1. Preheat the oven to 350°F (180°C). Line an 8-inch square baking pan with parchment paper, leaving overhang.
2. In a large bowl, melt the butter. Whisk in the granulated sugar and brown sugar until smooth and glossy.
3. Beat in the eggs one at a time, then stir in the vanilla extract. Whisk until the batter thickens slightly.
4. Sift the cocoa powder, flour, and salt over the wet mixture. Fold with a spatula just until no dry streaks remain.
5. Fold in the chocolate chips, then scrape the batter into the prepared pan and smooth the top. Tap the pan on the counter a few times.
6. Bake for 30 to 35 minutes, until a toothpick inserted in the center comes out with a few moist crumbs. Cool completely in the pan on a wire rack, then lift out by the parchment, slice, and dust with powdered sugar.

Notes

The cake will look underdone in the middle when you pull it from the oven. That’s intentional. It sets up as it cools into the fudgiest texture. If you’d like a cleaner crumb, chill the cooled cake for 15 minutes before slicing.