I packed all the fudgy, sprinkle-studded nostalgia of a Cosmic Brownie into one gloriously thick cookie cake. This is the kind of dessert that makes the whole table go quiet, then ask for seconds.

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I’m obsessed with this Cosmic Brownie Cookie Cake because it hits every snack-cake craving I’ve ever had, then piles on that thick cookie bite I can’t resist. I love the fudgy center, the chewy edges, the glossy chocolate vibe, and those rainbow candy bits staring back like they know I’m taking another slice.

And I am. No shame.

This is the kind of dessert I adore when I want something loud, sweet, and ridiculous in the best way. But my favorite part is how it feels like childhood boxed brownies got a massive, over-the-top bakery upgrade, minus the polite portions.

Ingredients

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Brownie mix brings that fudgy, nostalgic base.
Basically, it’s the shortcut hero here.
Cookie dough adds chewy edges and that soft, bakery-style center everyone fights over.
Chocolate ganache makes it glossy, rich, and a little dramatic in the best way.
Rainbow candy chips give the classic Cosmic Brownie look and a fun little crunch.
Eggs help everything hold together, so each slice stays thick and satisfying.
Butter adds richness and that warm, cozy flavor you can’t fake.
Vanilla makes the chocolate taste deeper, even if it seems like a tiny thing.
Chocolate chunks melt into pockets, so you’ll get gooey bites everywhere.
Plus, a pinch of salt keeps all that sweetness from going totally wild.

Ingredient Quantities

Do you want the ingredient quantities in US customary units or metric?

How to Make this

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1. Preheat oven to 350 F and grease or line a 9 or 10 inch round cake pan with parchment, letting some overhang for easy removal.

2. Make the cookie layer: cream 1 cup softened butter with 1 cup brown sugar and 1/2 cup granulated sugar until light, add 1 large egg and 1 teaspoon vanilla, then stir in 2 1/4 cups all purpose flour, 1/2 cup cocoa powder, 1 teaspoon baking soda and 1/2 teaspoon salt to form a soft dough; fold in 1 to 1 1/2 cups chocolate chips. Press the dough evenly into the bottom of the prepared pan.

3. Chill the pressed cookie layer in the fridge while you prepare the brownie layer so it holds shape.

4. Make the brownie batter: melt 6 ounces bittersweet or semisweet chocolate with 1/2 cup butter, whisk until smooth and cool slightly, then beat in 3/4 cup sugar, 2 large eggs, and 1 teaspoon vanilla. Fold in 1/2 cup all purpose flour and 2 tablespoons cocoa powder until just combined.

5. Pour or spread the brownie batter evenly over the chilled cookie layer, taking care not to mix the two layers together. Smooth the top with a spatula.

6. Bake in the preheated oven for 28 to 35 minutes, or until the brownie layer is set at the edges and slightly fudgy in the center; a toothpick inserted near the center should come out with a few moist crumbs.

7. Cool the cake in the pan on a wire rack for at least 30 minutes, then refrigerate for 1 hour to firm both layers for clean slicing.

8. Remove the cake from the pan using the parchment overhang and transfer to a serving plate; warm a knife and trim the edges if desired for a neat look.

9. Top generously with rainbow nonpareils or candy sprinkles to create the cosmic look, and let the cake sit at room temperature 15 minutes before slicing so it cuts cleanly.

Equipment Needed

1. 9 or 10 inch round cake pan
2. Parchment paper, scissors or kitchen shears to line the pan
3. Mixing bowls (one large, one medium)
4. Electric mixer or handheld whisk
5. Rubber spatula for folding and spreading
6. Wooden spoon or sturdy silicone spatula for cookie dough
7. Measuring cups and spoons
8. Small saucepan or microwave safe bowl for melting chocolate
9. Wire cooling rack and a sharp knife for trimming and slicing

FAQ

What is a Cosmic Brownie Cookie Cake? A hybrid dessert combining a fudgy brownie layer, cookie dough base, and a topping of colorful candy-coated chocolate pieces for a chewy, chocolatey cake meant to serve like a sheet cake.

Can I make this ahead of time? Yes. Bake and cool completely, then wrap and refrigerate up to 3 days or freeze up to 2 months. Bring to room temperature before serving for best texture.

How do I prevent the cookie layer from overbrowning? Watch baking time closely and tent loosely with foil if the top darkens too quickly. Using an oven thermometer helps ensure correct oven temperature.

Can I use a different candy topping? Yes. Swap the candy-coated chocolates for chopped chocolate, chocolate chips, sprinkles, or toffee bits. For color and texture similar to Cosmic Brownies use a mix of small candies and mini chips.

Is there an easy way to get clean slices? Chill the cake for 20 to 30 minutes, then cut with a sharp knife warmed under hot water and wiped dry between cuts for neat slices.

Can I make this gluten free or dairy free? For gluten free use a 1 to 1 gluten free flour blend and confirm all candies and baking powder are GF. For dairy free substitute vegan butter and dairy free chocolate; texture will be similar but slightly different.

How do I store leftovers? Store in an airtight container at room temperature up to 2 days or refrigerated up to 4 days. For longer storage freeze portions wrapped well for up to 2 months.

Cosmic Brownie Cookie Cake Recipe Substitutions and Variations

Would you like the ingredient quantities in US customary units or metric?

Butter: Substitute equal amount of vegan butter or refined coconut oil for a dairy free option
All purpose flour: Substitute 1 to 1 gluten free flour blend for a gluten free version; expect slightly different texture
Eggs: Replace each egg with 1/4 cup applesauce or 1/4 cup mashed banana for a vegan or egg free binder
Chocolate chips: Use chopped dark chocolate or candy-coated chocolate pieces for a different melt and texture

Pro Tips

1) Chill that cookie layer until firm before adding the brownie batter. It will keep the layers distinct and prevent them from blending together while you spread the top.

2) Cool the melted chocolate slightly before adding eggs. If the chocolate is too hot it can scramble the eggs and make the brownie batter grainy. Aim for warm but not hot.

3) Fold the dry ingredients into the brownie batter just until incorporated. Overmixing will make the top cake-y instead of fudgy.

4) For clean slices, refrigerate until well chilled, then warm a thin knife in hot water, wipe it dry, and make each cut in one smooth motion. Wipe and reheat the knife between slices for neat edges.

Cosmic Brownie Cookie Cake Recipe

Recipe by Samantha Dalling

0.0 from 0 votes

I packed all the fudgy, sprinkle-studded nostalgia of a Cosmic Brownie into one gloriously thick cookie cake. This is the kind of dessert that makes the whole table go quiet, then ask for seconds.

Servings

servings

Calories

kcal

Equipment: 1. 9 or 10 inch round cake pan
2. Parchment paper, scissors or kitchen shears to line the pan
3. Mixing bowls (one large, one medium)
4. Electric mixer or handheld whisk
5. Rubber spatula for folding and spreading
6. Wooden spoon or sturdy silicone spatula for cookie dough
7. Measuring cups and spoons
8. Small saucepan or microwave safe bowl for melting chocolate
9. Wire cooling rack and a sharp knife for trimming and slicing

Ingredients

Do you want the ingredient quantities in US customary units or metric?

Directions

Preheat oven to 350 F and grease or line a 9 or 10 inch round cake pan with parchment, letting some overhang for easy removal.
Make the cookie layer: cream 1 cup softened butter with 1 cup brown sugar and 1/2 cup granulated sugar until light, add 1 large egg and 1 teaspoon vanilla, then stir in 2 1/4 cups all purpose flour, 1/2 cup cocoa powder, 1 teaspoon baking soda and 1/2 teaspoon salt to form a soft dough; fold in 1 to 1 1/2 cups chocolate chips. Press the dough evenly into the bottom of the prepared pan.
Chill the pressed cookie layer in the fridge while you prepare the brownie layer so it holds shape.
Make the brownie batter: melt 6 ounces bittersweet or semisweet chocolate with 1/2 cup butter, whisk until smooth and cool slightly, then beat in 3/4 cup sugar, 2 large eggs, and 1 teaspoon vanilla. Fold in 1/2 cup all purpose flour and 2 tablespoons cocoa powder until just combined.
Pour or spread the brownie batter evenly over the chilled cookie layer, taking care not to mix the two layers together. Smooth the top with a spatula.
Bake in the preheated oven for 28 to 35 minutes, or until the brownie layer is set at the edges and slightly fudgy in the center; a toothpick inserted near the center should come out with a few moist crumbs.
Cool the cake in the pan on a wire rack for at least 30 minutes, then refrigerate for 1 hour to firm both layers for clean slicing.
Remove the cake from the pan using the parchment overhang and transfer to a serving plate; warm a knife and trim the edges if desired for a neat look.
Top generously with rainbow nonpareils or candy sprinkles to create the cosmic look, and let the cake sit at room temperature 15 minutes before slicing so it cuts cleanly.

Notes

Below you’ll find my best estimate of this recipe’s nutrition facts. Treat the numbers as a guide rather than a rule—great food should nourish both body and spirit. Figures are approximate, and the website owner assumes no liability for any inaccuracies in this recipe.