Preheat oven to 350ºF (180ºC). Line a 12 cup cupcake or muffin pan with paper liners.
In a small bowl, dissolve the espresso powder with 1 tablespoon of hot water. Set aside.
In a medium bowl, whisk or sieve together cake flour, baking powder, baking soda, salt. You don’t want clumps particularly check this when measuring the baking powder and baking soda.
Using a stand mixer and the paddle attachment, beat the butter and sugar on medium speed for 2-3 minutes until creamy and well combined.
With the mixer running, slowly drizzle in the oil. After adding all the oil, beat for another 2 minutes.
Add the eggs, one at a time, beating well after each addition. At this stage most of the sugar should be dissolved and the mixture should be thick, creamy and homogenous.
Whisk the milk and sour cream into the espresso powder mixture until combined.
With the stand mixer on low speed, add half of the flour mixture followed by half of the milk/espresso mixture. Mix until only just combined.
Stop and scrape down the sides of the bowl. Then repeat with the remaining ingredients.
Stop and scrape the side of the bowl then beat on medium speed for 30 seconds to thoroughly combine.
Scoop the batter into the cupcake liners and bake for 15-17 minutes or until the cupcakes have risen and a toothpick inserted in the middle comes out clean.
Cool for a minute or two then transfer to a wire rack to cook completely.
When completely cooled, frost with coffee buttercream frosting. I used the Wilton 1M decorating tip.
Notes
Top Tips
Completely dissolve the instant espresso powder in hot water.
Have all ingredients at room temperature.
Drizzle the oil in slowly so that it combines thoroughly.
Be gentle when adding the flour to the butter mixture. Excessive beating will cause tough cupcakes.