After baking, wrap the sponge cakes tightly in plastic wrap and chill them overnight. This firms up the cakes, making them easier to slice and stack without breaking.
Use a long serrated knife to cut each sponge horizontally into two even layers. Even layers help your cake look professional and stack neatly.
Place the first layer on a cake board or stand. Spread 2–3 tablespoons of chocolate fudge filling evenly over the surface, then top with the next sponge layer. Repeat this process until all layers are stacked.
Chill while stacking. After every 3–4 layers, chill the cake for 15–20 minutes. This helps the layers set and makes the cake more stable for frosting.
Apply a crumb coat. Spread a thin layer of chocolate buttercream over the cake to trap crumbs. Chill the cake for 20–30 minutes before applying the final layer of frosting.
Evenly spread the remaining buttercream over the top and sides of the cake for a smooth finish.
Warm the remaining chocolate fudge icing slightly in the microwave for 5-7 seconds and stir until it’s pourable. Drizzle it over the top and sides to create beautiful chocolate drips.
Decorate with any remaining chocolate frosting as desired. Refrigerate the cake for at least 1 hour, or overnight, to let the layers and frosting set perfectly.