Self Frosting Chocolate Cupcakes - Cupcake Fanatic

Ingredients

• 1 cup white miniature marshmallows
• 1 cup semi-sweet chocolate chips
• 1 egg, lightly beaten
• 1 1/2 cups all-purpose flour
• 1/2 cup cocoa powder
• 1/4 teaspoon baking powder
• pinch of salt
• 1/2 cup unsalted butter, room temperature
• 1 1/2 cups firmly packed brown sugar
• 1 egg
• 1 teaspoon baking soda
• 1 cup sour cream