01 -
Set your oven to 350°F. Line and grease a 9x9-inch square pan with parchment and butter or oil.
02 -
Combine 2 tsp lemon juice or vinegar with 2/3 cup milk. Stir and leave it aside.
03 -
Sift as you mix together flour, sugar, salt, baking soda, and baking powder to ensure no lumps stay behind.
04 -
Add the egg, oil, and buttermilk to the dry mixture. Stir until smooth and no dry spots remain.
05 -
Whisk together cocoa powder, instant coffee, and boiling water until smooth and shiny. This will enhance the chocolate flavor.
06 -
Gently fold the cocoa mixture into the batter until just mixed.
07 -
Pour the batter into the lined pan. Bake for 23-25 minutes until a toothpick inserted in the center has moist crumbs, not batter.
08 -
Let the baked cake sit in the pan at least 20 minutes to cool off.
09 -
Beat together sugar, vanilla, and chilled cream in a bowl until soft peaks just appear. Don’t go past this stage.
10 -
Add mascarpone a little at a time and mix slowly to combine. Don’t overmix or it’ll lose its fluff and get gritty. Adjust flavors to taste.
11 -
Remove the cake from the pan and cut off the crusts if needed. You can snack on those scraps later.
12 -
Clean the pan, line it with double parchment, and carefully move the cake back in with the top side exposed.
13 -
Dab strong coffee or espresso over the cake using a pastry brush. Make sure it’s damp but not soaked.
14 -
Use an offset spatula to layer the mascarpone cream evenly across the surface.
15 -
Move the pan into the fridge, leaving the cake to set for around 6 hours or overnight.
16 -
Carefully lift the cake using parchment edges and transfer it to a serving plate.
17 -
Use a sieve to sprinkle cocoa powder on top. Trim the edges for cleaner slices, if you prefer.
18 -
Cut into pieces and dig in!