Boston Cream Whoopie Pies (Edit recipe)

For the Whoopie Pies

1. Preheat the oven to 375 degrees F (190 degrees C) and line two baking sheets with parchment paper.
2. On another piece of parchment paper, trace 2" circles spaced about 2" apart.
3. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
4. In a large bowl with an electric mixer, beat the butter and sugars together for 2-3 minutes.
5. Mix in the egg and vanilla until fully combined.
6. In two additions, alternate folding in the dry ingredients and buttermilk with a rubber spatula.
7. Transfer the batter to a piping bag with a large round piping tip (I used Ateco 808).
8. Place your template under a piece of parchment paper on a baking sheet and pipe perpendicular to fill each circle.
9. Bake the whoopie pies for about 10 minutes or until just barely golden on the edges.
10. Allow to cool completely before assembling.

For the Pastry Cream

1. In a medium bowl, whisk the egg yolks, sugar, and cornstarch together for 2-3 minutes until light in color.
2. Heat the milk in a saucepan, and bring to a simmer or about 200 degrees F.
3. Once the milk is simmering, slowly pour half into the egg-sugar mixture, whisking at the same time to temper the eggs.
4. Pour everything back into the saucepan and heat over medium heat, whisking constantly as it thickens.
5. Once the pastry cream is thick and a few big bubbles come to the surface, continue whisking for one more minute, then remove from heat.
6. Immediately stir in the butter and vanilla.
7. Transfer the pastry cream to a bowl and press plastic wrap up against the surface to prevent a skin from forming.
8. Chill in the fridge (preferably) overnight or until ready to use.

For the Chocolate Ganache

1. In a medium bowl, heat the heavy cream in the microwave for about 30 seconds.
2. Stir in the chocolate until fully melted.

For the Assembly

1. Pair the whoopie pies up, then spread the chocolate ganache on the top ones. Allow to set for a few minutes.
2. Spread the pastry cream on the bottom ones and gently sandwich with the tops.