Chocolate Blackout Cupcakes

INGREDIENTS

2 oz

semisweet chocolate

1/4 cup

heavy cream

4 oz

bittersweet chocolate, finely chopped

1/3 cup

dark cocoa powder

1/2 cup

boiling water

3/4 cup

all-purpose flour

1/2 cup

granulated sugar

1/4 cup

packed light brown sugar

1/2 tsp

salt

1/2 tsp

baking soda

1/2 cup

sour cream or plain yogurt, at room temperature

1/4 cup

vegetable oil

large eggs plus one egg yolk, at room temperature

2 tsp

white vinegar

1 tsp

vanilla extract

8 oz

bittersweet chocolate, melted and cooled

3 cups

powdered sugar, sifted

1/4 cup

dark cocoa powder, sifted

8 oz

unsalted butter, at room temperature

1/4 tsp

fine salt

2 tsp

pure vanilla extract

2 tbsp

heavy cream