01 -
Set your oven to 170ºC (340ºF) for a normal oven. Prepare three 20 cm/8 in round baking pans by lining them with parchment. Brew your coffee and measure it out so it can cool off before you mix the other items together.
02 -
Gather a mixing bowl and sift flour, cornstarch, cocoa, both sugars, salt, baking powder, and soda. Stir it all to make sure it’s blended well.
03 -
In another bowl, whisk together coffee, eggs, sour cream, vanilla, and oil. Stir gently without overdoing it so the eggs aren’t overmixed.
04 -
Carefully add the wet mixture to the bowl with the dry ingredients, stirring gently until smooth and lump-free. Split the batter equally into your prepared pans and pop them in the oven for about 28-30 minutes. Check with a toothpick—it should come out clean.
05 -
Allow the cakes to sit in the pans on a wire rack for five minutes. Then, carefully remove them from the pans and let them cool down completely.
06 -
Take your coffee, mix it into a small bowl with the instant coffee, and stir until dissolved to help boost the flavor. Sift the powdered sugar and put it aside.
07 -
Whip butter with a paddle attachment on medium-high speed for 4 minutes. Clean off the sides of the bowl, then beat again for another 2. Gradually add your powdered sugar, vanilla, and coffee in two additions. Mix well each time and give a final 2-minute spin to blend everything in.
08 -
Slice off the dome of each cake layer so they’re flat. Place one layer on your turntable or plate, spread three big scoops of frosting on top, and level it off with a spatula. Stack the next layer and repeat. Finish with the last layer, apply a thin crumb coat over the cake, then spread and smooth the final frosting layer.