Pre-heat oven to 350 degrees F. Line about 18 regular-sized muffin tins with wrappers or roughly double that for mini-cupcakes.

In a small bowl, mix together espresso, cocoa powder and vanilla. Set aside to cool.

In a second bowl, combine flour, baking soda, baking powder and salt.

In a third large bowl (sorry), cream together butter and sugar until smooth.

Add in eggs, one at a time, mixing thoroughly after each one.

Next, add 1/3 of the flour mixture and 1/2 of the sour cream into the third bowl (butter/sugar/eggs) and blend together.

Repeat adding 1/2 of the flour mixture that's left and the rest of the sour cream and blend once more.

Mix in remaining flour along with the espresso mixture and beat thoroughly.

Pour batter into muffin pans, filling them about 2/3 full.

Bake for 16-18 minutes for regular-sized cupcakes (about 14-16 for mini-cupcakes) or until inserted toothpick comes out clean. Let cool completely.

Using an electric mixer, whip butter until nice and fluffy.

Add cocoa powder and mix in completely.

Next, whip in espresso until well-blended.

Gradually add powdered sugar until you reach the desired consistency of frosting.

Refrigerate frosting for about 10 minutes before spreading it on cupcakes (that should be completely cooled).

Enjoy!