01 -
Turn the oven on to 350°F and use parchment paper and butter or oil to prep a 9x9 inch pan.
02 -
To create a buttermilk substitute, combine 2/3 cup milk with 2 tsp white vinegar or lemon juice. Mix and let it sit for a bit.
03 -
Grab a bowl and put in the flour, sugar, salt, baking powder, and soda. Sift everything so you don't get clumps.
04 -
Crack in the egg and stir in the buttermilk and vegetable oil. Gently whisk this until smooth.
05 -
Stir cocoa powder and instant coffee into the boiling water in a smaller dish. Whisk until glossy. This wakes up the cocoa flavor.
06 -
Pour the cocoa and coffee mixture into the batter. Gently fold everything together until fully mixed.
07 -
Spread the finished batter into the pan and bake at 350°F for around 23-25 minutes. A toothpick poked in the center should come out with some crumbs.
08 -
Leave it in the pan to cool down for close to 20 minutes.
09 -
Whip vanilla, sugar, and chilled heavy cream in a bowl until it thickens. Don't whip it too long.
10 -
Mix in the mascarpone cheese in two rounds, using low speed. The cream should stay fluffy. If you overdo it, the texture might get grainy.
11 -
Once cooled, take the cake out of the pan and cut away the crusts. Don't waste too much—snack on them if you like.
12 -
After cleaning your pan, use two parchment paper sheets with edges hanging over to line it. Fit the cake back in, crumb side up.
13 -
Brush strong coffee or espresso lightly over the surface using a pastry brush, soaking it evenly but not too much.
14 -
Take the mascarpone cream and spread it evenly over the cake. An offset spatula can help with this.
15 -
Chill the cake in the fridge for about 6 hours or overnight so it all sets properly.
16 -
Lift the cake out of the pan using the parchment overhang once it's set. Move it to your serving plate.
17 -
For a cleaner look, trim the edges. Sift cocoa over the top using a fine mesh.
18 -
Cut into pieces and enjoy your treat!