Step 1

Preheat to 350F. Add papers to a cupcake tin.

Step 2

Sift the dry ingredients (including the sugar) into the bowl of a stand mixer and whisk to combine.

Step 3

Add the sour cream, buttermilk, eggs, and veggie oil into a large bowl and whisk together. Pour the hot coffee in while you whisk and set aside.

Step 4

Add the wet ingredients into the dry ingredients.

Step 5

Whisk until smooth and combined.

Step 6

Distribute batter evenly into the cupcake papers and bake for about 15 -20 minutes or until a toothpick inserted in the center comes out clean.

Step 7

Allow to cool.

Step 8

Add egg whites, sugar and salt in a bowl. Give the mixture a brief whisk.

Step 9

Place the bowl over a pan of simmering water. Make sure the water does not touch the bowl. Whisk the egg whites occasionally while it warms up. When the mixture has warmed, whisk it constantly. You will heat the mixture until it reaches an internal temperature of 160ºF or until it's not grainy between your fingers.

Step 10

Transfer the bowl to a stand mixer, mix with a whisk attachment until you get room temperature glossy peaks.

Step 11

Switch to a paddle attachment and while the mixture is running on low, add tablespoon sized dollops of room temperature butter making sure to let the butter incorporate before you add the next piece. Once all the butter is incorporated, go ahead and add the vanilla extract.

Step 12

Drizzle in the melted and cooled chocolate while the mixer is running on low. Scrape the bowl down and mix again. You can now transfer it to a piping bag or to a ziplock bag to store in the freezer.

Step 13

Use a large star tip to pipe a swirl of buttercream onto the cooled cupcakes. Start at the center, squeeze and lift the tip while rotating the cupcake back and forth. Stop squeezing the piping bag while you continue to lift for a nice tip to the dollop.