Whoopie Pies

Name: Whoopie Pies
Prep time: 40 min
Cook time: 55 min
Total time: 55 min
Yield: 16 pieces
Ingredients: 8 ½ oz whole milk; 1 ½ tbsp lemon juice; 8 oz light brown sugar; 4 oz unsalted butter; 1 large egg; 1 tsp vanilla extract; 9 oz all-purpose flour; 2 oz Dutch-processed cocoa powder; 1 tsp espresso powder; 1 tsp baking powder; ½ tsp baking soda; ¾ tsp salt; 10 oz unsalted butter; 16 oz confectioners sugar; 1 tsp vanilla extract; &frac18; tsp salt; 7 oz marshmallow creme