One Bowl Chocolate Cupcakes with Nutella Swiss Buttercream Frosting

INGREDIENTS

1 cup

all purpose flour

1 1/4 cups

granulated sugar

1/4 cup

plus 2 tablespoons (45 grams) Dutch process cocoa powder (I used Valrhona)

1 tsp

baking soda

1/2 tsp

salt

1/2 cup

vegetable oil

1/2 cup

sour cream

3/4 cup

room temperature water

1 tbsp

white vinegar

1 tsp

pure vanilla extract

large egg, at room temperature

large egg whites (4 ounces, 113 grams)

4 oz

granulated sugar

salt

1 1/2 cups

(3 sticks, 339 grams) unsalted butter, at room temperature and cut into 2 inch chunks

1/2 cup

Nutella