Homemade Cosmic Brownies

Preparation - Preheat the oven to 350°F. Place a rack in the middle of the oven and preheat. Lightly spray an 8x8-inch square baking pan with nonstick cooking spray and line with a sheet of parchment that completely covers the bottom with a slight overhang on two sides. Lightly spray the pan once more, taking care to grease the parchment and sides.

Brownie Batter - Make the chocolate mixture: In a small saucepan, melt the butter over medium heat until just melted, swirling the pan as needed to avoid browning, 2 1/2 to 3 minutes. Remove from the heat. Add the cocoa powder and oil to the hot butter and whisk to fully incorporate and bloom the cocoa. Add the chopped bittersweet chocolate and whisk until fully melted and combined. Set aside to cool slightly while you whisk the egg mixture.

Brownie Batter - Whisk the sugars, eggs, and vanilla together: In a large bowl, vigorously whisk the granulated sugar, light brown sugar, eggs, and vanilla until lightened in color and well combined, about 2 minutes. Scrape the chocolate mixture into the bowl with the egg mixture and whisk to combine.

Brownie Batter - Combine the dry ingredients and add to the batter: In a small bowl, whisk the flour, baking powder, and salt to combine. Add the flour mixture to the chocolate mixture and whisk until just combined. It's okay if there are some flour streaks. Use a rubber spatula to give the batter a few good folds, taking care to scrape the bottom of the bowl to get all the dry ingredients, until all the flour is incorporated.

Baking - Transfer the batter to the pan and bake: The brownie batter will be on the thicker side. Scrape the batter into the prepared pan and spread into an even layer using the spatula, a small offset spatula, or the back of a spoon. Bake the brownies on the middle rack of the oven the top has a paper-thin crinkly appearance, and a toothpick comes out clean or with moist crumbs (not wet batter), 25 to 28 minutes. The brownies will likely puff around the 25-minute mark with a toothpick still coming out wet, then settle in the next couple minutes. Once the brownies settle, they are typically ready. Cool the brownies completely in their pan set over a wire rack, about 1 hour.

Ganache - Make the ganache: Once the brownies are cool, make the ganache. Combine the chopped chocolate and pinch of salt in a small bowl or large glass measuring cup. In a small saucepan (you can rinse, dry, and reuse the same one from the brownies), heat the heavy cream over medium heat until it comes to a simmer with vigorous bubbling just around the edges and steam coming off the surface, 1 to 2 minutes. Immediately pour the hot cream over the chocolate, let sit for a minute, then stir until smooth and silky and all the chocolate is melted.

Assembly - Pour the ganache over the brownies: Lift the brownies out of the pan by the parchment overhang and transfer to a cutting board. If desired, you can flip the brownies over so that the bottom is facing up for a very even surface to spread the ganache. While the ganache is still warm and spreadable, pour it over the brownies and use a small offset spatula or the back of a spoon to spread into an even layer. It's okay if it doesn't look completely smooth at first. The ganache will settle into itself. Try to avoid pushing the ganache over the sides. Top the ganache with the candy-coated chocolate chip sprinkles as desired.

Serving - Set, slice, and serve: Transfer the brownies to the refrigerator to chill until the ganache is set and firm enough to cut, about 30 minutes. Use a hot, dry knife (I like to run my knife under hot water and then wipe it dry with a clean towel) to cut the brownies, wiping the knife clean between each cut. If cutting into bars and adding the signature perforated line, first cut the brownies down the center to create two long halves. Lightly drag the side of an offset spatula, back of a butter knife, or skewer in a straight line down the middle length of each half to create the signature look, taking care to not drag through all the way to the brownie. Then, cut each half into 4 pieces with the indentation running crosswise to yield 8 bars total. Alternatively, you can cut the brownies into 16 squares and skip the perforated line altogether. The brownies can be stored in a single layer in an airtight container at room temperature for up to 2 days or chilled in the refrigerator for up to 1 week.