Mocha Nutella Cupcakes

INGREDIENTS

6 tbsp

unsalted butter, room temperature

3/4 cup

sugar (155g)

6 tbsp

sour cream, room temperature

1/2 tsp

vanilla extract

large egg whites (room temperature, divided)

1 1/4 cups

all-purpose flour (163g)

2 tsp

baking powder

1/4 tsp

salt

2 tbsp

hot water

3 tbsp

instant espresso coffee powder

6 tbsp

milk, room temperature

1/2 cup

salted butter, room temperature

1/2 cup

vegetable shortening

4 cups

powdered sugar, divided

3/4 cup

chocolate hazelnut spread, such as Nutella

5 tbsp

water or milk