Fudgy Brownie Cupcakes with The Best Peanut Butter Frosting

INGREDIENTS

1 cup

butter (2 sticks, 8 ounces)

1/2 cup

semisweet chocolate chips

1 1/2 cups

lightly packed brown sugar

1 tbsp

vanilla extract

large eggs

1 cup

all-purpose flour

3/4 cup

unsweetened cocoa powder

1 tsp

baking powder

1/2 tsp

salt

6 tbsp

butter, softened

3/4 cup

creamy peanut butter

2 cups

powdered sugar

salt

1/2 tsp

vanilla extract

1/4 cup

heavy cream, plus more if needed for consistency

Mini peanut butter cups for garnish (optional)