The BEST Chocolate Cupcakes

1 c. all-purpose flour
1 c. sugar
1/2 c. cocoa
1 tsp baking powder
1/2 tsp baking soda
1/4 tsp salt

1/2 c buttermilk, room temp
1/2c vegetable oil
1 egg, room temp
1 tsp vanilla

1/2 c boiling water
1 tsp espresso powder

Preheat oven  to 350 degrees.  Line a muffin tin with 18 cupcake liners and set aside.
In the bowl of a stand mixer fitted with the paddle attachment, combine flour sugar, cocoa, baking powder, baking soda and salt.
In a small bowl, whisk together the buttermilk, oil, eggs, and vanilla.  With mixer on low speed, add the liquid to the dry ingredients, then increase speed to medium for about 20 seconds,  until well combined. 
Stir espresso powder into the boiling water. Carefully add to the cake batter.  Beat on medium-high speed for 1 minute to combine well.

Fill cupcake liners 2/3 full.  Bake for 18 minutes or until toothpick inserted in the center comes out clean.

Remove from oven and allow to cool for 5 minutes in pan, then remove cupcakes to wire rack and cool completely before frosting.

Rich Chocolate Frosting: 
1 c (2 sticks) butter, slightly softened
2 tsp vanilla
3 c powdered sugar
1/2 tsp salt
1/2 c cocoa
4 oz. melted chocolate
4 T heavy cream

Place butter and vanilla in mixing bowl and beat on high speed until smooth.  In another bowl, sift together the powdered sugar, cocoa and salt.  With mixer on low speed, add sugar mixture  to the butter, mixing to combine.  Add cooled melted chocolate and stir together.  Add heavy cream and beat on high speed for 3 minutes until frosting is light and fluffy.