Pre-heat oven to 350F / 180C. Grease and flour or spray two 9 inch / 23cm round cake pans.
In a large bowl beat together for approximately 2 minutes, the milk, oil, sugar, flour, and eggs then sift in the cocoa, baking powder, salt add the vanilla, beat again until smooth.
Pour the batter evenly into the prepared cake pans. Bake for approximately 30-35 minutes or until a toothpick comes out clean or with a few crumbs attached. Remove from oven, let cool in the pan for about 15-20 minutes then remove from the pan to a wire rack, let cool completely.
In a small bowl add the warm water and the instant coffee stir to dissolve, or use brewed coffee.
Place the Nutella in a small bowl and place the bowl over a small pot of boiling water let the Nutella thin so that it is easier to cover the cake (about 5 minutes).
Place one of the cakes (slice off a little of the rounded top part of both cakes so they sit firmly on the plate) up side down on a serving plate and drizzle with ½ the coffee, cover with half the Nutella or chocolate ganache** or chocolate spread. Cover lightly (tent style) and refrigerate for 10-15 minutes to firm up the filling.
While the cake is in the fridge, in a medium/large bowl, whip the cream and Mascarpone until very thick. Remove the cake from the fridge and cover with half the whipped cream mixture.
Place the second cake on top and drizzle with the remaining coffee, cover with the remaining Nutella, again cover lightly and refrigerate for 10-15 minutes. Remove the cake from the fridge and cover with the remaining whipped cream mixture. Cover and refrigerate the cake for approximately 5-6 hours before serving or better yet overnight. Bring to room temperature (30-45 minutes) then dust with cocoa or chocolate flakes if desired before serving. Enjoy!
** If you don' like Nutella you can always substitute with a chocolate ganache. In a heatproof bowl place 4 ounces chopped dark chocolate heat ½ cup whipping cream (or whole cream) to almost boiling then pour over chopped chocolate let sit for 10 minutes and then stir until smooth, let cool until thickened and spreadable.
Notes
To make homemade cake flour - for every cup of all purpose flour, remove two tablespoons and replace with two tablespoons of corn starch. Be sure to sift the flour and cornstarch together a couple of times, this way it is sure to be properly combined and lump free. Cake flour in cakes will give you a very tender texture and fine crumb, it will also help the cake to rise.Take any cold ingredients out of the refrigerator an hour ahead of time or sooner if it’s cool in your kitchen. Room temperature ingredients blend easier, creating a silky batter or dough, which will help to create a light tender baked good.To thin Nutella, you can place it in a bowl and place the bowl over a pot of hot water. This will allow steam to warm the underside of the bowl of Nutella and allow it to thin out. Alternatively you can heat Nutella in a microwave safe bowl in the microwave in 10 second increments, taking out to stir each time.Since this cake is made with a whipped cream frosting it needs to be stored in the refrigerator. Store covered in the refrigerator for up to 3-4 days. Allow it to come to room temperature before serving for the best flavor and texture.The cake can also be frozen, but it is better to freeze the cake layers before decorating them. Cool completely then wrap the sponge cakes in plastic wrap then aluminum foil. Store frozen for up to three months. Thaw covered in the refrigerator then decorate as you wish.