step 1
Preheat oven to 350 degrees F (180 degrees C).
step 2
Spray the bottom and sides of an 8-inch square cake pan with Nonstick Cooking Spray (as needed). Cut a piece of parchment paper to the dimensions of the cake pan and fit it into the bottom (this is an extra layer of protection against sticking). Set aside.
step 3
In a large bowl, beat the Unsalted Butter (1/3 cup), Brown Sugar (3/4 cup), and Granulated Sugar (2 Tbsp) until fluffy. Use a rubber spatula to scrape down the bowl.
step 4
Add the Eggs (2), and Vanilla Extract (1 tsp) and beat until combined.
step 5
Add the Buttermilk (3/4 cup) and beat again -- mixture will look curdled.
step 6
Sift together the Unsweetened Cocoa Powder (1/2 cup), All-Purpose Flour (1 cup), Baking Soda (1/4 tsp), Baking Powder (1/2 tsp), and Salt (1/2 tsp) and beat into the butter mixture on low speed until just combined.
step 7
Transfer the batter into the prepared pan and use a spatula to spread it out evenly.
step 8
Bake for 30-35 minutes until a cake tester comes out clean.
step 9
Cool the cake for 5-10 minutes in the pan, then invert it onto a cooling rack and cool cake completely before frosting.
step 10
To make the frosting, first, melt the chocolate. Place the Unsweetened Chocolate (1/3 cup) in a small microwaveable glass bowl and heat in a microwave oven in short 15-20 second increments until the chocolate has melted into a glossy pool. Don't stir. Cool to room temperature.
step 11
In a large bowl, combine the Powdered Confectioners Sugar (1 1/2 cups), Unsalted Butter (1/2 cup), Salt (1/8 tsp), Heavy Cream (1 Tbsp), and Vanilla Extract (1/2 tsp). Beat on medium speed until smooth and creamy.
step 12
Add the room temperature chocolate and beat until well combined.
step 13
Turn the mixer up to a medium high or high and beat it for a minute more.
step 14
Place the cake upside down on your cake stand or platter.
step 15
Spoon the frosting into the center of the cake and use an offset spatula to push the frosting out from the center in short little swirls to give it that dreamy icing landscape. You can frost the sides if you like.
