Preheat the oven at 170ºC/340ºF conventional oven and line 3x 20 cm/8 inch baking pan with parchment paper.
Start by making the coffee and weigh it out so it can cool down a bit while preparing the other ingredients.
360 g warm coffee or water
In a bowl, sift all of the dry ingredients together. Give it a stir to make sure everything has been combined.
360 g all-purpose flour, 2 tablespoon cornstarch, 300 g granulated sugar, 150 g dark brown sugar, 75 g unsweetened Dutch cocoa powder, 1 ½ teaspoon baking powder, 1 ½ teaspoon baking soda, 1 ½ teaspoon salt
In another mixing bowl add all of the wet ingredients, including the coffee, and with a hand whisk, whisk them together until combined.
165 g vegetable oil, 270 g sour cream 14-18%, 3 large eggs, 3 teaspoon vanilla extract
Slowly pour the wet ingredients into the dry while gently stirring it all together. Make sure there are no lumps left in the batter. Using a rubber spatula, scrape down the sides of the bowl, and give the cake batter a final mix so everything has been incorporated.
Pour the cake batter into the prepared baking tins and bake them for 28-30 minutes or until a cake tester comes out clean.
Let the cakes cool on a cooling rack. After 5 minutes, gently remove the cakes from the cake tins and let the cakes cool down completely.