Preheat the oven (with the oven rack in the middle) to 350 degrees. Spray two 8 or 9-inch cake pans (these cake pans are my favorite) with cooking spray and line the bottoms with parchment paper (I did this by tracing the bottom of the cake pan on parchment paper and the cutting out the circle and putting it in the bottom of the cake pan. Don't skip this step, it'll really get those cakes out perfectly without sticking to the bottom!)

For the cake, in a small saucepan, combine the butter and 1 cup water and 1 tablespoon instant coffee over medium heat. Heat until the butter is melted, stirring occasionally.

In a medium bowl, whisk together the eggs, sour cream, and vanilla.

In a large bowl (or the bowl of a stand mixer), whisk together the flour, granulated sugar, brown sugar, cocoa powder, baking soda, baking powder, and salt. Add the butter mixture. Use an electric mixer on low speed to mix until just combined. On medium speed, mix in the sour cream mixture.

Dividing evenly, scrape the batter into the prepared pans. Bake for 20-30 minutes, until a toothpick inserted into the center of the cakes comes out with a few moist crumbs attached. Place the pans on a wire cooling rack and let cool for 25 minutes. Run a paring knife around the edge of each cake to loosen it from the pan. Then invert the cakes onto the rack, remove the parchment paper, and let cool completely.

For the frosting, put the chocolate chips in a medium bowl. In a small saucepan over medium heat, heat the cream until it is hot. Pour the cream over the chocolate and let stand for 1 minute. Now gently whisk until creamy and smooth.

Scoop out 3/4 of the chocolate mixture into another bowl and set aside the remaining frosting for now Let the 3/4 cup of mixture cool, stirring occasionally, for about 40 minutes, or until it is spreadable, creamy, and holds its shape.

Place one cake on a serving plate, bottom side up. Spread the top with the frosting in an even layer all the way to the edge. Top with the other cake, bottom side up.

If the remaining frosting is still pourable, pour it over the top of the cake and gently spread it around so that it slowly drips over the edge. If the frosting is not pourable, reheat it. Gently reheat the remaining frosting by filling a medium saucepan with 2 inches of water and placing over medium heat. Let come to a low simmer. Place the bowl of frosting over the water (the bottom of the bowl should not touch the water). Stir until it is melted and pourable. Immediately pour the frosting over the top of the cake.

With a metal spatula, quickly spread it to evenly cover the top and let the frosting drip down the sides. Once the frosting is set, slice and serve.