S’mores Cupcakes

INGREDIENTS

1 1/2 cups

graham cracker crumbs

1/4 cup

sugar

5 1/3 tbsp

unsalted butter, melted

1/2 cup

plus 1 tablespoon Dutch-process cocoa powder

1/2 cup

plus 1 tablespoon hot water

2 1/4 cups

all-purpose flour

3/4 tsp

baking soda

3/4 tsp

baking powder

1/2 tsp

salt

2 sticks

plus 1 tablespoon unsalted butter, at room temperature

1 2/3 cups

sugar

large eggs, at room temperature

1 tbsp

vanilla extract

3/4 cup

sour cream

large egg whites, at room temperature

1 cup

sugar

1/4

tsp. cream of tartar

1 tsp

vanilla extract