• Preheat oven to 350 degrees. Lightly grease two 9-inch cake pans. Cut out two circles of parchment and fit one to the bottom of each cake pan.

Brownie layer:

• In a microwave-safe bowl, melt the butter and chocolate chips for 1 minute. Stir until the bowl is no longer warm. If needed, heat an additional 20-30 seconds until totally smooth. Whisk in the sugars.
• In a large bowl, beat the eggs on medium-high speed until very frothy and bubbly, about 3-4 minutes. Lower the speed and mix in the butter and sugar mixture, then the vanilla and instant coffee (if using).
• Add the flour, cocoa powder, and baking powder. Mix until just combined.  Pour the batter into one of the prepared cake pans.

Chocolate cake layer:

• In a large bowl, beat the oil, brown sugar, and sugar for 2-3 minutes until combined. Whip in the eggs, one at a time, then the vanilla and yogurt. Add the flour, cocoa powder, black cocoa powder, baking powder, baking soda, and salt. With the mixer running, stream in the buttermilk until the batter is just combined. Do not overmix. Pour into the second cake pan.
• Bake the layers for 30-40 minutes. Start checking the cake at 30 minutes, as it may bake faster than the brownie layer.
• Cool the cake layer in the pan for 10 minutes, then run a knife around the edges to loosen and invert onto a wire rack. Peel off the parchment from the bottom.
• The brownie layer will take longer to cool sufficiently. Cool on the counter for 20 minutes, then refrigerate at least another 25 minutes before attempting to remove. To do this, run a knife around the edges to loosen, then carefully invert onto a plate, then flip upright onto the wire rack.

hot fudge sauce:

• In a small saucepan, whisk the chocolate chips, heavy cream, and cocoa powder until the granules dissolve and the sauce thickens and becomes super smooth, about 4-5 minutes. Remove the pan from the heat and stir in the vanilla. Let cool.

Cake batter buttercream:

• Whip the butter, vanilla, and cake batter extracts until combined, then add 6 cups of the powdered sugar, in 1/2 cup increments as the mixer is running on medium low speed. Add heavy cream 1 tablespoon at a time to smooth out the texture. Crank the mixer to high, and beat until very light and fluffy, about 2-3 minutes. You may need an extra tablespoon of two of cream to achieve the desired texture. Scrape down the sides of the bowl with a spatula, as needed, to properly incorporate all the ingredients.
• Place the brownie layer on a cake stand or flat plate. Frost the top generously, about 1/2 inch thick, then set the chocolate cake layer atop and frost thoroughly. Smooth the frosting out as best you can with a bench scraper.
• Spread the hot fudge sauce across the top of the cake with an offset spatula or spoon, letting some dribble down the sides. Let set for 15 minutes. Use any remaining buttercream to pipe swirls on top of the cake. Garnish with maraschino cherries!