1 tbsp unsweetened cocoa powder (mix with 1 tsp instant coffee powder if you like.)
For the cake top
1 tbsp unsweetened cocoa powder
1. Cut a piece of parchment paper to cover the bottom and sides of a jelly-roll pan.
2. Sift flour into a medium bowl and set aside. Pre-heat the oven to 190C degree.
3. Beat eggs with sugar in a medium bowl until creamy (about 3~5min) with an electric hand mixer.
4. Gradually add the flour and mix the batter until all the lumps are gone, using spatula.
5. In a small cup, add butter and milk and microwave for 10 to 15 sec at 600w. Mix to melt. Then add into the mixture (#4). Scrape the bottom of the bowl to ensure all the ingredients have been incorporated evenly.
6. Pour the batter onto the prepared sheet pan and spread into an even layer. Flatten the surface with the spatula.
7. Bake for about 10~12min or until light golden in color.
8. Remove from the oven, immediately loosen the edges of the cake from the pan gently. Flip the cake upside down. Peel off the parchment paper you just used for baking (you could even use printing paper sheets). Let the cake cool completely.
9. Place the sponge cake onto the plate you are going to use. Then spread coffee onto the cake evenly. Let it cool down to room temperature. Using a sieve, dust the cocoa powder (mix with 1 tsp coffee powder) over the cake.
10. In a bowl, add mascarpone, cream cheese and sugar. Beat until just combined and smooth. Gently fold the whipped cream (soft-peak) into the cream mixture and mix well.
11. Spread the cream mixture over the sponge cake. Dust the top with cocoa powder.
12. Refrigerate for a few hours or overnight before serving.