Step 1

First, make the frosting as it will need time to chill and thicken while the cupcakes bake.

Step 2

In a large bowl using a hand or stand mixer with the paddle attachment, mix the butter and sugar until smooth and fluffy (about 3 minutes).

Step 3

Meanwhile, add the chocolate and corn syrup to a heat safe bowl and microwave in 30 second intervals until smooth, stirring between each interval.

Step 4

Then microwave the sour cream for about 30 seconds or until thinned and smooth.

Step 5

Mix the warm sour cream into the warm chocolate along with the vanilla. Stir to combine.

Step 6

With the mixer running, slowly pour the chocolate into the sugar and butter. Mix until smooth.

Step 7

The frosting should be pretty thin at this point, like the consistency of freshly made pudding.

Step 8

Place the bowl into the refrigerator and allow the frosting to chill and thicken for about 45 minutes. Stir the frosting every so often to ensure it chills evenly.

Step 9

Preheat the oven to 350F and line a cupcake pan with 12 liners and a second pan with 3 liners (this recipe makes 15 cupcakes).

Step 10

In a large mixing bowl, whisk together the flour, sugars, cocoa, baking soda, baking powder, and salt.

Step 11

In a separate bowl, whisk together the oil, eggs, vanilla, and sour cream.

Step 12

In a measuring glass, combine the hot water and espresso powder.

Step 13

Pour the oil mixture into the dry ingredients and stir to combine.

Step 14

Halfway through mixing, pour in the coffee mixture and continue to stir until smooth.

Step 15

Distribute the batter between the liners, filling each halfway full.

Step 16

Bake for 15-17 minutes, or until puffed and a toothpick in the center comes out clean with a few moist crumbs.

Step 17

Transfer the cupcakes to a cooling rack as soon as possible, careful not to touch the pan as it will be very hot.

Step 18

Allow the cupcakes to cool completely before frosting.

Step 19

By the time the cupcakes have cooled, the frosting should be thickened and spreadable. If it’s TOO thick, remove a few spoonfuls and microwave until thin and smooth. Then mix the warm frosting into the bowl of chilled frosting.

Step 20

Frost with a piping tip or with a handmade swirl and top with sprinkles of choice. Enjoy!