Preheat the oven to 350°F. Lightly spray two 9-inch round cake pans with baking spray (Baker’s Joy or a generic version). Set them aside.

Add the cake mix, water, oil, and egg whites to a medium-sized mixing bowl. Use a handheld mixer on medium speed to mix until completely incorporated and no lumps remain.

Evenly divide the batter between the prepared pans. Bake for 22-25 minutes, or until a toothpick inserted comes away clean. Allow the cakes to cool completely.

While the cakes are cooling, add the granulated sugar, espresso powder, and Kahlua to the hot water. Stir to combine. Set it aside.

Add the mascarpone cheese to a small mixing bowl and stir until the cheese is smooth.

Using a stand mixer with a wire whip attachment or a large mixing bowl and a handheld mixer on high speed, beat the cold heavy cream and vanilla extract until stiff peaks form, about 3-5 minutes.

Reduce the mixer speed to medium, and slowly add the granulated sugar. Increase the speed to medium-high and beat for another 1-1½ minutes.

Lower the speed to low. Slowly add ¼ of the smoothed mascarpone at a time, mixing until combined and smooth.

Add ⅔ cup of the frosting to a piping bag fitted with a large star-shaped decorating tip (I used Wilton 1M). Cover the remaining frosting with plastic wrap and refrigerate until you are ready to assemble and decorate the cake.

Once the cakes are completely cooled, use either a long serrated knife or a cake leveler to slice each cake into 2 layers, giving you 4 layers total.

Place the bottom layer either on a large flat serving plate or a round cake board.

Use a pastry brush to generously brush on the cooled coffee mixture.

Spoon on 1-1¼ cups of the mascarpone filling. Use an offset spatula to smooth the filling over the surface of the bottom layer. Repeat for the next 2 layers.

For the final layer, brush the coffee mixture over the surface of the top layer. Spoon 1¼-1¾ cups of the mascarpone filling over the top.

Spread the remaining filling around the outside of the layers, smoothing as you go.

Add the 1 tablespoon of unsweetened cocoa powder to a sifter. Gently shake the cocoa powder over the top of the cake.

Pipe swirls of the reserved mascarpone filling around the edge of the cake top, as well as in the center of the cake. Place 1 coffee bean into the center of each swirl. Slice and serve.