Preheat oven to 350 F. Line cupcake tins with paper liners.
In a large bowl, combine flour, sugar, cocoa powder, baking soda, baking powder and salt. Add eggs, milk, vanilla extract and butter. Mix with an electric mixer mix for 2 minutes. Then hand stir in the coffee.
Pour the batter into each cupcake liner until the bottoms are covered. Place a brownie piece into each cupcake liner and fill with batter until ⅔ full.
Bake for 22 minutes, or until inserted toothpick comes out clean.
Allow to cool in pans for 5 minutes and then place cupcakes onto wire racks to cool completely.
Hot Fudge Frosting
In a bowl, combine confectioners' sugar and cocoa powder. Set aside.
In a bowl, cream butter. Gradually beat in sugar mixture, milk and hot fudge sauce. Mix until fluffy.
Spread or pipe frosting onto the cupcakes.
Recipe by Sugar, Spice and Family Life at https://sugarspiceandfamilylife.com/2017/08/brownie-stuffed-chocolate-cupcakes-recipe.html