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–+ servings

Whoopie Pies with Boiled Milk Frosting

thetimelessbaker
A chocolate cake-like sandwich cookie filled with an old fahsioned smooth and creamy boiled-milk frosting.
5 from 1 vote
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Prep Time 20 minutes
Cook Time 9 minutes
Frosting time 1 hour 15 minutes
Total Time 2 hours 45 minutes
Course Dessert
Cuisine American
Servings 18 assembled sandwich cookies

Equipment

  • cookie sheets
  • parchment paper or silicone baking mats
  • medium-sized cookie scoop
  • piping bag, plastic baggie or off-set spatula
  • small saucepan
  • mixing bowls of various sizes

Ingredients
  

For the Cookies

  • 3/4 cup granulated sugar
  • 1/4 cup vegetable oil
  • 1 large egg, room temperature
  • 1/4 cup sour milk (see notes), or buttermilk
  • 1/4 cup cocoa powder
  • 1/4 cup hot water, heated to at least 110°F
  • 1/2 tsp vanilla extract
  • 1/2 tsp baking soda
  • 1/2 tsp baking powder
  • 1/2 tsp salt
  • 1 1/3 cup all-purpose flour

For the Boiled Milk Frosting

  • 3 tbsp all-purpose flour
  • 3/4 cup milk, 2% or whole
  • 1 cup granulated sugar
  • 3/4 cup butter, softened
  • 1 tsp vanilla extract

Instructions
 

For the Cookies

  • Preheat oven to 375°F and line cookie sheets with parchment paper or silicone baking mats.
  • Combine sugar and oil in bowl of a mixer, mix until just combined.
  • Add egg and mix until just combined.
  • In small bowl, whisk cocoa until there are no lumps. Slowly pour in hot water and stir until cocoa is dissolved.
  • Slowly add the dissolved cocoa to creamed mixture.
  • Add in vanilla.
  • Sift or whisk remaining dry ingredients in medium-sized bowl.
  • Alternate adding the dry ingredients and the sour milk, beginning and ending with the dry ingredients.
  • Using a medium-sized cookie scoop, scoop dough onto lined baking sheets about 2 inches apart, carefully forming uniform sized circles.
  • Bake for 7-9 minutes, or until the tops of each cookie are just set (they should not jiggle when pan is moved).
  • Remove from oven and allow to cool on baking sheets 1-2 minutes. Then, carefully move to a wire baking rack or parchment lined flat surface to cool completely.
  • Frost when completely cool.

For the Boiled Milk Frosting

  • In small saucepan, whisk milk, flour and sugar.
  • Whisk over medium heat until thickened (almost as thick as a pudding).
  • Immediately remove from heat and pour into a bowl. Allow to cool at room temperature.
  • In large mixing bowl, whip softened butter until light, about 2 minutes.
  • Add cooled flour mixture and whip on high speed, until light and fluffy.
  • Add in vanilla extract.
  • To pipe frosting between two cookies: pour frosting into a piping bag (or baggie). Snip the tip of the bag and slowly pipe the frosting onto the bottom of one cookie, top with the bottom of another cookie, "sandwiching" them together.
  • Alternately, use an offset spatula instead of a piping bag to frost the bottom of one cookie and top with the bottom of another cookie, "sandwiching" them together.

Notes

  • To make sour milk, add 1 tsp. of white vinegar to milk. You can substitute buttermilk instead. 
  • Boiled milk frosting can be made ahead of time, up to 48 hours. Store chilled. When ready to assemble whoopie pies, bring to room temperature and re-whip. 
  • Assembled whoopie pies will keep up to 72 hours when stored chilled, in an airtight container.
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