-
Preheat the oven to 350 degrees F. Line a 12 cup muffin tin with cupcake liners.
-
Whisk together the flour, baking soda, baking powder, and salt in a medium mixing bowl.
-
In a separate large mixing bowl, whisk together the cocoa powder, chocolate chips, and boiling water until smooth. Add the sugar, sour cream, oil, eggs, and vanilla. Whisk until combined.
-
Add the dry ingredients to the wet ingredients all at once. Mix until smooth and combined.
-
Fill the cupcake liners about ¾ of the way with the batter. Bake for 20 minutes until a toothpick inserted into the center comes out clean. Transfer cupcakes to a wire rack to finish cooling.
-
To make the frosting, bring about a cup of water to a simmer in a saucepan. Add the egg whites and sugar to a heatproof bowl. Place the bowl over the simmering water. Whisk the egg whites and sugar for three minutes until the sugar is dissolved. Remove bowl from the heat.
-
Using a handheld electric mixer, beat the egg whites until stiff peaks form, about six minutes. Beat in the vanilla extract.
-
Transfer frosting to a piping bag or a large gallon plastic storage bag. Cut the corner off the storage bag and frost the top of each cupcake. Sprinkle some shaved chocolate on top for a little something extra.