Why You’ll Love This Recipe

I like this recipe because it’s simple to make but feels like a special treat. The dough comes together easily, and the chocolate ganache adds a decadent finishing touch that makes each cookie irresistible. The rainbow chips remind me of classic lunchbox desserts, but the flavor is deeply chocolatey and rich. I also appreciate that they stay soft for days—if they even last that long!

Ingredients

(Note: All ingredient amounts are listed in the recipe card below.)

2 1/2 cups all-purpose flour
1/2 cup unsweetened cocoa powder
2 teaspoons baking powder
1/2 teaspoon cream of tartar
1/2 teaspoon salt
1 cup salted butter, softened
1 cup semi-sweet chocolate chips
2/3 cup light brown sugar, packed
1/2 cup granulated sugar
2 eggs
2 teaspoons vanilla extract
Chocolate Ganache: 1 cup semi-sweet chocolate chips, 1/4 cup heavy whipping cream
Rainbow chocolate chips, for decoration

Directions

I start by preheating my oven to 350°F (175°C) and lining baking sheets with parchment paper. In a medium bowl, I whisk together the flour, cocoa powder, baking powder, cream of tartar, and salt.

In a large mixing bowl, I cream the softened butter with both sugars until the mixture becomes light and fluffy. Then, I add the eggs one at a time, mixing well after each, and stir in the vanilla extract.

Next, I gradually add the dry ingredients to the wet mixture, stirring just until combined. I fold in 1 cup of semi-sweet chocolate chips to give the dough extra richness.

Using a spoon or cookie scoop, I drop spoonfuls of dough onto the prepared baking sheets, spacing them about 2 inches apart. I bake the cookies for 10–12 minutes, just until they’re set around the edges but still soft in the center.

While the cookies cool, I make the chocolate ganache. I heat the heavy cream until it begins to simmer, then pour it over the chocolate chips and stir until smooth and glossy. Once the cookies have cooled completely, I spread or drizzle the ganache over the tops and finish with a generous sprinkle of rainbow chocolate chips. I let the ganache set before serving.

Servings and Timing

This recipe makes about 24 cookies. The prep time is 20 minutes, the cook time is 12 minutes, and the total time is about 32 minutes.

Variations

Sometimes I like to switch things up by using dark chocolate chips instead of semi-sweet for a deeper flavor. I’ve also tried adding a touch of espresso powder to the dough to enhance the chocolatey taste. For a festive twist, I replace the rainbow chips with holiday-colored sprinkles. If I want a saltier-sweet flavor, I sprinkle a pinch of flaky sea salt on top of the ganache before it sets.

Storage/Reheating

I store the cookies in an airtight container at room temperature for up to 5 days. If I make them ahead, I sometimes refrigerate the dough and bake it fresh when needed. The ganache-topped cookies can also be refrigerated, and I bring them to room temperature before serving. To reheat for a fresh-from-the-oven texture, I warm a cookie in the microwave for about 10 seconds.

FAQs

How do I keep the cookies soft and chewy?

I make sure not to overbake them—removing them when the centers still look slightly soft keeps them chewy.

Can I use unsalted butter instead of salted?

Yes, I can use unsalted butter and just add an extra 1/4 teaspoon of salt to balance the flavor.

Can I freeze the cookie dough?

Absolutely. I scoop the dough onto a baking sheet, freeze it until solid, and store it in freezer bags for up to 3 months.

How should I store the cookies after adding ganache?

I keep them in a single layer or separate layers with parchment paper to prevent sticking.

Can I make the ganache thicker?

Yes, I reduce the cream slightly or let the ganache cool longer before spreading.

What if I don’t have cream for the ganache?

I can use half-and-half or even milk, though the ganache will be slightly less rich.

Can I use mini chocolate chips instead of regular ones?

Yes, mini chips mix evenly into the dough and melt beautifully.

Do I need to chill the dough before baking?

No, but if my kitchen is warm, I sometimes chill the dough for 10–15 minutes to prevent spreading.

Can I double the recipe?

Yes, this recipe doubles easily, and I bake in batches to avoid overcrowding the pan.

What can I use instead of rainbow chips?

I like using M&M minis, crushed candy pieces, or colored sprinkles for variety.

Conclusion

I love making these Cosmic Brownie Cookies because they’re the ultimate treat for chocolate lovers. The rich, fudgy centers, glossy ganache, and cheerful rainbow topping make them both nostalgic and decadent. Whether I bake them for a party, a gift, or just to brighten my day, these cookies always bring a smile—and a burst of chocolatey happiness—with every bite.