Preheat oven to 300°F and liberally butter two 9-inch round pans (See important NOTE below).
Place the chocolate chips in a small bowl and pour the hot coffee over top. Let mixture stand, stirring occasionally, until chocolate is melted and the mixture is smooth.
Into a large bowl, whisk together sugar, flour, cocoa powder, baking soda, baking powder, and salt.
In the bowl of a stand mixer, beat the eggs until lightened in color and slightly frothy, about 2 minutes.
In a large measuring cup, stir together the oil, buttermilk, and vanilla.
Slowly add the buttermilk mixture to the eggs, mixing until well combined. Do the same with the chocolate-coffee mixture.
Add the dry ingredients to the wet mixture in two or three batches, mixing until just combined. Resist the urge to overmix the batter. You want to mix until all the dry ingredients are visibly incorporated.
Place the cake pans on a large baking sheet. Divide the batter between the prepared pans and bake in the middle of the oven until a tester inserted in the centers comes out clean, roughly 60-75 minutes (check after an hour).
Cool the cakes in the pans for 15 minutes and then carefully invert them onto cooling racks to finish cooling.
Cake layers may be made a day or two ahead and kept, wrapped well in plastic wrap, in the fridge. I actually prefer to do the cakes ahead because they are easier to frost if chilled.
In a saucepan, bring cream, sugar, espresso powder, salt, and corn syrup to a simmer over moderately low heat, whisking until sugar is dissolved.
Remove pan from heat and add chocolate, whisking until chocolate is melted. Cut butter into pieces and add, whisking until smooth.
Transfer the mixture to a bowl and cool, stirring occasionally, until spreadable. This should take 20-30 minutes. You want it to be of a fudgy consistency so that it does not run out the sides of the cake during assembly. I let it cool until it is a similar consistency to frosting.
In the bowl of a stand mixer, cream together the cream cheese and butter with the whisk attachment for 2 minutes, or until they are fluffy, creamy, and well combined.
Add in the salt and half the powdered sugar and whisk on LOW to combine.
Meanwhile, dissolve the espresso powder in the vanilla extract and then add it to the frosting, mixing to combine.
Add more powdered sugar as needed to reach a thick and creamy consistency (for me, this is usually 5 cups of powdered sugar, but depending on the moisture of your ingredients, you may need a little more).
Place the first cake layer on a cake pedestal (or plate). Spread the cooled fudge filling mixture on top of the first layer. Do not go all the way to the edge. Top with the second cake layer.
Dollop half of the espresso frosting on top of the cake and work it around the top and down the sides, swirling the frosting evenly as you go. This will serve as a “crumb coat.” Place the cake in the fridge for 20-30 minutes so the first layer of frosting can set.
Spread the second layer of frosting over top of the first (this will cover up any cake crumbs that have worked their way into the first layer of frosting), smoothing everything out as you go. Garnish the cake with finely chopped chocolate-covered espresso beans (an optional step!).
Slice and serve! Store any leftover cake well wrapped in the fridge and allow enough time to let it come back to room temperature before serving again (See NOTE below).
