Step 1

Preheat oven to 350 degrees.

Step 2

Whisk together the flour, cocoa, baking soda and salt in a medium bowl and set aside.

Step 3

Combine the sugar, buttermilk, oil, egg, and vanilla in a large bowl and mix on medium speed with a mixer until all ingredients are combined. Add the dry ingredients and mix just to combine. Do not over mix.

Step 4

Bake the cupcakes for 20 to 25 minutes until a toothpick inserted into the center of one comes out with moist crumbs on it. Transfer cupcakes to a wire rack to cool. While the cupcakes are cooling make the Peanut Butter Buttercream.

Step 5

Combine the sugar, egg whites and salt in the bowl of a stand mixer. Mix for about 30 seconds on medium speed. The mixture will look frothy. Place the mixing bowl over a pan of simmering water. Slowly whisk the mixture until it reaches 160 degrees on an instant-read thermometer, (about one minute), remove from heat and replace the bowl on the mixer stand. Using the whisk attachment, whisk the mixture on medium-high speed until the mixture becomes thick like whipped cream from a can, but not stiff.

Step 6

With the mixer on medium speed, add the butter one piece at a time and mix until combined and creamy. Add the peanut butter and vanilla and mix on medium speed until the peanut butter is incorporated and the mixture is light and creamy.

Step 7

Refrigerate the peanut butter buttercream for 30 minutes.

Step 8

Attach a 1/2″ round tip, #808 or #2A tip to a pastry bag, and fill the pastry bag 2/3rds full with the buttercream.  Starting in the center of each cupcake, hold the tip straight upward and alternately apply pressure, and lift tip in an upward motion, forming a  swirled ice cream look.  Place the cupcakes upright in a cupcake tray and place in freezer for 30 minutes until really chilled and firm.

Step 9

Melt the chocolate in a small bowl and add the oil. Blend until smooth. Holding the bottom of each cupcake, dip the peanut butter buttercream into the chocolate and turn the cupcake to coat most of the buttercream. Lift cupcake from chocolate and slowly turn the cupcake while allowing the excess chocolate to drip off. Place each cupcake upright in a cupcake holder/tray. The chocolate will set up within one minute.

Step 10

Store cupcakes in an airtight container.  Cupcakes will stay fresh for up to 5 days.