Preheat the oven at 175ºC conventional oven and prepare a half sheet baking pan (23x33 cm) baking pan with parchment paper.
Start by boiling some water and weigh out the water so it can cool down a bit while preparing the other ingredients.
190 g boiling water
In a bowl sift all of dry ingredients together. Give it a stir to make sure everything has combined.
270 g all-purpose flour, 300 g granulated sugar, 75 g unsweetened cocoa powder, 1 teaspoon instant espresso powder, 1 teaspoon baking powder, 1 ½ teaspoon baking soda, 1 teaspoon salt
In another mixing bowl add all of the wet ingredients and with a hand whisk, whisk them together until combined. Be sure to not mix the ingredients too vigorously so the eggs don’t get over mixed.
240 g buttermilk, 110 g vegetable oil, 3 large eggs, 2 teaspoon vanilla extract, 190 g boiling water
Slowly pour the wet ingredients into the dry while gently stirring it all together. Make sure there is no lumps left in the batter.
Pour the cake batter into the prepared baking pan and bake it for 30-35 min or until a cake tester comes out clean.
Let the cake cool on a cooling rack. After 15 min, gently remove the cake from the baking pan to a cooling rack and let it cool down completely.