Homemade Cosmic Brownies (TikTok Viral)

These thick, fudgy homemade cosmic brownies are 10x better than storebought! Topped with a creamy homemade chocolate ganache (made without heavy cream!) and rainbow chip sprinkles, these brownies are truly out-of-this-world delicious.

Course Dessert

Cuisine Brownie

Keyword homemade cosmic brownie, little debbie

Prep Time 15

Total Time 1

Servings

Calories 253kcal

Author Melissa Rose

Ingredients

¾ cup unsalted butter (i.e 1.5 sticks; you will be melting this)
1 ½ cups granulated sugar
½ cup light brown sugar
3 large eggs + 1 egg yolk
1 tablespoon vanilla extract
1 teaspoon salt
¼ teaspoon baking soda
2 tablespoons cornstarch
1 ½ cups Hershey's cocoa powder (100% cacao natural unsweetened) I highly recommend using this specific cocoa or another quality cocoa. Off-brand cocoa often tastes bad so use at your own risk...you've been warned!
1 cup all-purpose flour
¼ cup vegetable oil

Easy Chocolate Ganache (see notes section below for a firmer, traditional ganache using heavy cream)

1 ½ cups semi-sweet chocolate chips (i.e. 12 ounce bag) *see notes section below for notes on certain brands; we found Nestle Toll House or Ghiradelli brands firm up the best
6 tablespoons unsalted butter chopped into small cubes
½ cup whole milk (you can also use 2% or 1% but the ganache will be less firm so you will need to refrigerate and/or freeze brownies so frosting sets; see notes below)

Topping

Rainbow chip sprinkles you can get the Wilton brand at most craft stores or on Sweetapolita (use code DESIGNEATSPRINKS15“ for 15% site-wide!)

US Customary - Metric

Instructions

To Make Brownies:

Before you start, be sure to read through the tips & tricks in the post above for ingredient notes, step-by-step photos, and FAQ's!
Preheat oven to 350° F.
In a large microwave-safe bowl, add unsalted butter (¾ cup, i.e. 1 ½ sticks), granulated sugar (1 ½ cups), and light brown sugar (½ cup). Microwave for 2 minutes, stir, then microwave for 30 more seconds. Carefully remove bowl from microwave and stir until smooth. Let cool for 2-3 minutes.
To the butter and sugar mixture, stir in the eggs (3 large), egg yolk (1 large), vanilla extract (1 tablespoon), salt (1 teaspoon), baking soda (¼ teaspoon), and cornstarch (2 tablespoons). Once combined, mix in cocoa powder (1 ½ cups) and all-purpose flour (1 cup) until just combined (I recommend mixing by hand to prevent from overmixing). Stir in vegetable oil (¼ cup).
Spray a light metal 9x13 pan with nonstick cooking spray, then press on a piece of parchment paper to cover the bottom and long sides to create a parchment sling (photo in post above!). This will help you lift the brownies out of the pan so that you can cut them nicely. Spread brownie batter into the prepared pan until smooth.
Note: baking these in glass or dark metal pans may cause them to overbake and become bitter. If that's the only pan you have, lining with parchment on all sides becomes more crucial. You will also likely need to bake them for less time to prevent overbaking.
Bake at 350° F for 24-26 minutes or until center looks set and no longer jiggles when you gently shake the pan (do not overbake). Let cool completely in pan (once the pan is no longer hot to the touch, you can speed up cooling by placing pan in refrigerator.

To Make Easy Chocolate Ganache

Before you begin: Note that the ganache will not completley "harden" as a traditional ganache with heavy cream would. See notes section below for tips & tricks, as well as an alternate recipe using heavy cream.
In a medium-sized bowl, place semi-sweet chocolate chips (1 ½ cups) and chopped unsalted butter (6 tablespoons).
In a separate medium-sized bowl or large liquid measuring cup, heat milk (½ cup) in the microwave for 1 ½ - 2 minutes, or until it begins to bubble (it’s important that your measuring cup or bowl is at least 3x taller than the milk line, as it will expand when it’s heating and can easily overflow). You can also heat this on the stove; remove it once it begins to steam.
Use a hot pad to carefully remove milk from the microwave and pour over the chocolate chips and butter (do not stir yet!). Allow to sit for about 3 minutes, then use a whisk to stir until smooth and creamy. It may take a minute or two for it to come together; it often looks separated at first. Allow to cool for about 30 minutes before pouring over cooled brownies.

To Decorate:

Once brownies are cooled, re-stir the ganache and spread over brownies. Immediately top with rainbow chip sprinkles (or any other sprinkles you have!). Place in refrigerator for 1-2 hours to help the frosting harden (you can speed this up by putting in the freezer!).
Use a large knife to slice bars ( I highly recommend that your bars are chilled or frozen before slicing to ensure a clean cut).
Storage: Refrigerate the frosted bars. You can also keep at room temperature for up to 1 day (just note the frosting will soften). They get even better & fudgier on Day 2!

Notes

Wil the ganache harden?: Since we’re doing a simple ganache using butter & milk, the ganache won’t be as “hard’ at room temperature as a traditional ganache would be (see next note for an alternate recipe!). Because of this, I recommend storing the frosted brownies in the fridge if you don’t want the frosting to soften. After spreading on the ganache and adding the sprinkles, refrigerate for 1-2 hours for the frosting to set (before cutting, if you’re trying to get clean edges!). The ganache will start to soften at room temperature, so I recommend storing them in the refrigerator or freezer to keep it firm.

Want a more firm ganache that hardens? If you want the frosting to stay “hard” at room temperature, you will need to use heavy cream. To make a firm ganache, follow the instructions below but use ½ cup heavy cream and 1.5 cups chocolate chips (no butter).

Can I use 2% or 1% milk instead of whole milk? We knew you'd ask, so we tested the ganache with both! Both actually work just fine but refrigerating or freezing the frosted bars becomes more crucial, as the ganache doesn't firm up as well.

A note on chocolate chip brands: The brand you use in the ganache will impact how firm it will set in the fridge. We tested this ganache using 4 different common semi-sweet chocolate chip brands. Nestle Toll House was #1 in producing the firmest ganache, Ghiradelli #2, Hershey's #3, Costco brand #4. All are comparable taste-wise but do firm up a bit differently. You can see my full comparison here!

Cocoa Powder: I tested this recipe using Hershey’s Unsweetened Cocoa powder, as it’s my favorite cocoa for brownies. Take note that different brands may cause the brownie taste and texture to be a bit different.

Nutrition is just an estimate and calculated with an automated system.

Nutrition