Preheat oven to 350 degrees F (175 degrees C).
Into a mixing bowl, add All-Purpose Flour (1 3/4 cup), Granulated Sugar (2 cup), Unsweetened Cocoa Powder (3/4 cup), Baking Soda (2 teaspoon), Baking Powder (1 teaspoon), and Salt (to taste). Whisk together until combined.
Add Buttermilk (1 cup), Egg (2), Vanilla Extract (1 teaspoon), and Vegetable Oil (1/2 cup). Mix well to form a batter.
Add Coffee (1 cup) and whisk until smooth.
Transfer batter into two 9-inch cake pans lined with parchment paper.
Bake for 20-25 minutes.
Let the cakes cool completely, then place them in the freezer as you make the frosting.
Into the bowl of a stand mixer with a whisk attachment, add Heavy Cream (2 cup). Mix on low for 1 minute.
Increase the speed and mix until the mixture starts to thicken and soft peaks begin to form.
Add Unsweetened Cocoa Powder (1/4 cup) and Powdered Confectioners Sugar (1/4 cup), as well as a mixture of Instant Coffee (1 tablespoon) dissolved in Heavy Cream (2 tablespoon). Mix on low until combined.
Add Vanilla Extract (1 teaspoon). Mix until stiff peaks form. Set mixture aside.
Into the bowl of the stand mixer using a paddle attachment, add Salted Butter (1 cup), Powdered Confectioners Sugar (2 cup), and Unsweetened Cocoa Powder (3/4 cup). Mix until combined.
Add remaining Powdered Confectioners Sugar (2 cup), Milk (2 tablespoon), and Vanilla Extract (1 teaspoon). Mix until combined. Add additional milk as needed until you have a creamy chocolate frosting.
Spread one chocolate cake with the coffee-chocolate cream.
Place the other cake over top and spread the top and sides with the chocolate buttercream.
Place the cake in the freezer for 20 minutes.
Spread with another thin layer of the chocolate buttercream.
Decorate cake according to your preference.