Preheat oven to 350 degrees. Line two 12-cup muffin tins with cupcake liners (only 6 cupcake liners on the second pan). This recipe makes 18 cupcakes.
Combine the dry ingredients: onto a large bowl, sift the all-purpose flour, cocoa powder, baking soda, baking powder, salt, and instant espresso powder (optional). After sifting the dry ingredients, give it another whisk until evenly combined. Set aside.
Wet ingredients: In another large bowl, combine the vegetable oil, granulated sugar, brown sugar, vanilla, eggs, and buttermilk until well combined.
Add the dry ingredients to the wet ingredients, and combine without over-mixing. Add the very hot water, and combine evenly.
Fill each cupcake liner ONLY halfway full (very important!). The batter will be very thin. Tip: use a measuring cup with a spout to pour the batter easily.
Bake about 18-20 minutes, until a toothpick inserted in the middle comes back clean and the cupcake springs back. Don't open and close the oven when baking to avoid collapse cupcakes. When ready, remove cupcakes from pan and let cool completely.
Frost your cupcakes with your favorite buttercream frosting. Try my dulce de leche frosting.