Make the cake: 

1. Preheat the oven to 350F. Line 3, 6″ pans with parchment and coat the bottom and sides thoroughly with nonstick cooking spray.
2. In a large bowl, whisk together the flour, sugar, baking soda, espresso powder, and salt. Add the oil and sour cream, stirring to combine.
3. Gradually stream in the cold brew, whisking between additions. Add the vanilla extract and whisk in eggs one at a time.
4. Evenly divide the batter between your three pans and bake for 40-45 minutes, rotating halfway through. The cakes are done when a tester comes out clean and/or when gently pressed in the center, the cake springs back. Let cakes cool for 10 minutes, then remove from pans and continue to cool on a wire rack for about 30 minutes before you even think about frosting the cake. In fact, I recommend wrapping the cakes in plastic wrap and popping them in the refrigerator for about an hour. These cakes are very soft and very tender, so if you decide to frost when they’re still warm, you’re going to have a bad time.

Make the ganache:

1. Gently heat the heavy cream either in a double broiler or in short bursts in the microwave until hot but not scalding. Add the 1/2C of semisweet chocolate and allow the heat to do its thing for 15 seconds before beginning to stir.
2. Stir until completely melted and then stir in the remaining 1T of chocolate until melted. This added chocolate will help get your ganache thick enough to slice without spilling out of the cake but not so thick that it hardens if refrigerated. Set aside and allow to cool completely while you make the buttercream.

Make the buttercream:

1. In a small, microwave-safe bowl or cup, gently heat the heavy cream in the microwave until warm. Add the espresso powder and stir until completely combined and no granules are left. Store in the refrigerator to cool until needed. 
2. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter at med-high speed until lighter in color and increased in volume (about five minutes).
3. Reduce the speed to low and slowly beat in the powdered sugar. Scrape down the bowl as needed and once all the sugar is added, increase the speed to high and continue beating until light and fluffy.
4. Add the salt and reducing the speed to med-high, slowly stream in the cream/espresso mixture. Scrape down the bowl to make sure everything is combined. Beat on high for another 5 minutes, or until desired consistency is reached. 

Assembly – Part 1:

1. Lop off the tops of your cakes to create an even base (and enjoy the treat that is cake tops). Pick your bottom layer and spread a layer of coffee buttercream ontop. 
2. Using a piping bag, or ziplock bag with a corner snipped off, create a border of coffee buttercream around the edge to act as a barrier for your ganache. We’re basically making a kiddie pool out of buttercream.
3. Add a shallow layer of ganache. We aren’t trying to fill the kiddie pool to the top, just an even layer at the bottom, so nothing comes spilling out when we put the next layer on. 
4. Stack your next cake layer ontop and repeat the coffee buttercream/ganache process. Stack the last cake layer ontop and store in the refrigerator while you make the whipped cream. Or, do what I do, and take a break here to eat some lunch or watch a show, so you know your cake is extra firm when you are ready for the final assembly and decorating. 

Make the whipped cream:

1. In the clean bowl of a stand mixer fitted with the whisk attachment, whisk the heavy cream on high speed until thickened and soft peaks are forming.
2. Reduce the speed slightly and slowly add in the powdered sugar. Once all the sugar is added, turn off the mixer and scrape down the bowl.
3. Turn the mixer back on to med-high speed and begin adding bits of mascarpone a little at a time until you can no longer see any of the pieces. Add the vanilla and mix on high speed until a thick whipped cream consistency is reached—we’re looking for medium peaks. 

Assembly – Part 2:

1. Pull your cool and perfectly stacked cake out of the refrigerator. To cover the cake, I like to fill a piping bag, fitted with a large circular tip, with the whipped cream and firmly trail but if you don’t have that or prefer the “spackle” method, go for it. 
2. I do a crumb coat of whipped cream and then stick it back in the fridge to cool while I refill my piping bag. This recipe yields just enough frosting to pipe a crumb coat and a final coat plus a little decor on top which I did using a star-tip. Top with chocolate covered espresso beans and enjoy!