Preheat your oven to 350°F (175°C). Grease and line a 9x13-inch baking pan with parchment paper. Cream together 1 cup of granulated sugar and 1 cup of softened unsalted butter until light and fluffy, about 3-5 minutes. Add 4 large eggs, one at a time, mixing well after each addition. In a separate bowl, whisk together 1 cup of all-purpose flour, 1/2 cup of unsweetened cocoa powder, 1 teaspoon of baking powder, and 1/4 teaspoon of salt. Gradually add this dry mixture to the wet ingredients, mixing until just combined. Pour the batter into the prepared baking pan and spread it evenly. Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean. Allow the cake to cool completely in the pan.
While the cake cools, make the coffee syrup by combining 1 cup of cooled brewed espresso with 1/4 cup of coffee liqueur, if using. Poke holes in the top of the cooled cake with a fork and brush the espresso mixture generously over the cake.
Prepare the chocolate ganache by heating 1 cup of heavy cream over medium heat until it simmers. Remove from heat and add 8 ounces of chopped semisweet chocolate. Stir until melted and smooth, then stir in 1 teaspoon of vanilla extract.
For the espresso buttercream, beat together 1/2 cup of softened unsalted butter and 1 cup of powdered sugar until creamy. Gradually add in 2 tablespoons of the coffee syrup, mixing until smooth.
Assemble the cake by placing the cooled almond sponge on a serving platter. Pour half of the chocolate ganache over the cake, spreading it evenly. Chill for 30 minutes. Spread a layer of the espresso buttercream over the ganache, then repeat with the remaining ganache.
Drizzle with 1/2 cup of dark chocolate ganache for decoration. Chill the cake in the refrigerator for at least 120 minutes before slicing and serving.