1. Make the Chocolate Cappuccino Cake Layers:

• Preheat and Prep: Preheat oven to 350°F (175°C). Grease and flour three 8-inch round cake pans. Alternatively, line the bottoms with parchment paper and grease the parchment and sides.
• Combine Dry Ingredients: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt until well combined.  
• Add Wet Ingredients: Add the room-temperature milk, vegetable oil, room-temperature eggs, and vanilla extract to the dry ingredients. Beat with an electric mixer (hand mixer or stand mixer) on medium speed until well combined.
• Add Hot Coffee Mixture: In a small bowl or measuring cup, stir the instant coffee granules into the boiling water until dissolved. Carefully pour the hot coffee mixture into the cake batter and mix on low speed until smooth. The batter will be thin.
• Divide Batter: Divide the batter evenly among the three prepared cake pans.
• Bake: Bake for 30-35 minutes, or until a wooden toothpick inserted into the center comes out clean.
• Cool: Let the cakes cool in the pans for 10 minutes before inverting them onto a wire rack to cool completely. Ensure cakes are completely cool before frosting.

2. Make the Chocolate Coffee Frosting:

• Beat Butter: In a large bowl, using an electric mixer, beat the softened butter until creamy and smooth.
• Add Dry Ingredients: Gradually add the powdered sugar and cocoa powder, beating on low speed until just combined, then increase speed and beat until smooth.
• Add Wet Ingredients: Add the vanilla extract and the cooled strong brewed coffee. Beat until the frosting is smooth, fluffy, and reaches a spreadable consistency. If frosting is too thick, add a teaspoon more coffee or milk. If too thin, add more powdered sugar.

3. Assemble and Frost the Cake:

• Level Cakes (Optional): If the cake layers have domed tops, use a large serrated knife or cake leveler to slice a thin layer off the tops to create a flat surface.
• Frost First Layer: Place one cooled cake layer on a serving plate or cake stand. Spread a layer of chocolate coffee frosting evenly over the top.
• Add Second Layer: Carefully place the second cooled cake layer on top. Spread another layer of frosting over the second layer.
• Add Third Layer: Place the third cooled cake layer on top.
• Frost Cake: Frost the top and sides of the entire cake with the remaining frosting.
• Garnish (Optional): Decorate the cake with chocolate shavings, if desired.
• Serve