Boston Cream Whoopie Pies

      There are times when you need a nice, elegant layer cake.  And there are times when you need a whoopie pie.
      Layer cakes are great, but when you need to give someone or carry around a dessert, something portable like whoopie pies are perfect.
       Boston cream pie is traditionally served in layers, but I decided to turn it into a whoopie pie so that my sister could give it to her friend for her birthday.  So these Boston cream whoopie pies combine two different pies:  whoopie pie and Boston cream pie.
        All it is is a vanilla sponge cookie-shaped-cake-thing topped with pastry cream, and another cake with chocolate ganache on top.  Seriously, anything filled with cream is delicious.
        This whoopie pie is like a miniature Boston cream pie that you don't have to share with anyone.  It's amazing.  

First, you have to make the pasty cream and chill it for a few hours.

Whip some egg whites to soft peaks.  The added egg whites helps the whoopie pies to hold their shape better.

Beat butter and sugar together until creamy, and then mix in the egg yolk and the vanilla.

Whisk together the dry ingredients.

Alternate mixing in the dry ingredients in 3 batches and mixing in the milk in 2 batches.

Fold in some of the egg whites to temper the mixture, and then fold in the rest.

Place the batter in a piping bag.

Pipe round circles 1-2" wide and smooth them with a spatula.  I made some big ones and some small ones.  

Bake until the center springs back when you lightly poke it.

Fill with the cream and top with chocolate ganache.

Enjoy!

 Boston Creme Whoopie Pies

makes 12-24 (depending on size)

adapted from Tracey's Culinary Adventures

Ingredients

For the pastry cream:

1 cup half-and-half (or 1/2cup heavy cream plus 1/2cup whole milk)

3 egg yolks

1/4 cup sugar

pinch of salt

2 tablespoons all-purpose flour

2 tbs unsalted butter, cubed

3/4 tsp vanilla extract

For the Cookie:

2-1/4 cups all-purpose flour

1-1/2 tsp baking powder

3/4 tsp salt

1/2 cup (1 stick or 4oz) unsalted butter, room temperature

3/4 cup sugar

1 large egg yolk plus two large egg whites

1/2 tsp vanilla extract

1/2 cup whole milk

For the chocolate ganache:

1/4 cup heavy cream

2 oz semisweet chocolate, chopped

Directions

1. Make the pastry cream a few hours ahead of time or the day before.  In a small saucepan, scald the half-and-half (it should be steaming and have a few bubbles coming to the surface). Meanwhile, whisk together the egg yolks, sugar, salt, and flour in a medium bowl.  Slowly add the half-and-half to the egg yolk mixture while whisking constantly.  Return to the saucepan over medium heat and cook, whisking constantly, until it's slightly thickened.  Lower the temperature to medium-low and continue cooking, still whisking, until bubbles burst on the surface.  Strain into a bowl and refrigerate for at least 2 hours. 
2. For the cookie: Preheat the oven to 350*F and line two baking sheets with parchment paper. Whisk together the flour, baking powder, and salt and set aside.
3. Cream together the butter and sugar, then add the vanilla and egg yolk.  Mix until well-combined.
4. Add 1/3 of the dry ingredients to the egg mixture and stir until incorporated.  Then add half of the milk and stir. Then repeat, alternating dry ingredients with milk.  
5. Beat the egg whites to soft peaks and then fold  1/3 of it into the other mixture.  Then fold in the rest.
6. Place the batter in a piping bag and pipe circles 1"-2" wide onto the baking sheets.  Smooth the tops with a spatula and bake for 8-10 minutes, until the centers spring back when lightly touched.  Cool on baking sheets, then move to a wire cooling rack. Pair up cookies that are the same size.
7. For each pair of cookies, spoon or pipe some filling on one and then sandwich the other cookie on top.  
8. Make the ganache by bringing the heavy cream to a boil, and then pouring it over the chocolate in a bowl.  Stir until smooth.  Then, dip the whoopie pies in it, or wait for it to cool and spread it over the tops of the cookies.