Preheat the oven to 350°F/180°C (160°C fan oven), line a muffin pan with cupcake liners.
In a bowl, combine cocoa powder with espresso powder, flour, baking soda, baking powder, and salt.
In a separate bowl, whisk the eggs with sugars, oil, vanilla extract and milk.
Add the dry ingredients to the wet ingredients, and gently stir until just combined. Do not over mix the batter.
Pour the batter into cupcake liners ¾ full. Bake for 20 minutes or until a toothpick inserted in the center of a cupcake comes out clean.
Remove from the oven, and allow to cool down completely. As you wait, make the chocolate buttercream.
To make the chocolate buttercream:
In a large bowl using a hand mixer, or using a stand mixer that’s fitted with a whisk or a paddle attachment. Beat the butter at medium speed for 1 minute until creamy.
Decrease the speed to low, and gradually add the powdered sugar, cocoa powder, heavy cream, vanilla extract, and salt and beat again.
When the sugar is mixed in, increase the speed to high and beat for 3 minutes.
If the frosting is too thick, add cream and beat again. If it’s too thin, add powdered sugar and beat again.
Frost the cupcakes using a Wilton 1M piping tip, and decorate with chocolate sprinkles if desired.
Notes
Be patient and allow the cupcakes to cool down completely after they’re out of the oven! If you try to frost warm cupcakes, your frosting will melt and slide right off the side.
Storing unfrosted cupcakes at room temperature: Let the chocolate cupcakes cool completely and then store them in an airtight container for up to one week.
To storefrosted cupcakes in the refrigerator: Once you’ve decorated your cupcakes with buttercream, they should be stored in the fridge in an airtight container.
Storing unfrosted cupcakes in the freezer: Unfrosted chocolate cupcakes will keep well in the freezer for up to 2 months. Let them cool completely then store them in a freezer-safe container or a zip-top bag.