Boston Cream Pie Cupcakes

Directions:
Make the Pastry Cream:
In a saucepan, heat the milk until just about to boil. Meanwhile, whisk egg yolks, sugar, cornstarch, flour, and salt in a bowl until smooth. Slowly whisk in the hot milk. Return to the saucepan and cook over medium heat, stirring constantly until thickened (2–3 minutes). Remove from heat, stir in vanilla, and let cool. Cover with plastic wrap (touching the surface) and refrigerate.
Bake the Cupcakes:
Preheat oven to 350°F (175°C). Line a muffin pan with cupcake liners. In a bowl, whisk together flour, baking powder, and salt. In a separate bowl, cream butter and sugar until light and fluffy. Beat in eggs one at a time, then vanilla. Alternate adding the dry ingredients and milk, beginning and ending with the dry. Mix until just combined.
Fill and Bake:
Divide batter evenly among cupcake liners (about 2/3 full). Bake for 18–20 minutes or until a toothpick comes out clean. Cool completely on a wire rack.
Fill the Cupcakes:
Once cooled, use a small knife or cupcake corer to remove the center of each cupcake. Fill with chilled pastry cream using a spoon or piping bag.
Make the Ganache:
Heat the heavy cream in a small saucepan until simmering. Pour over chopped chocolate in a bowl and let sit for 2 minutes. Stir until smooth. Add butter if using.
Top the Cupcakes:
Spoon or dip the tops of filled cupcakes into the ganache. Let set at room temperature or refrigerate briefly to firm up the chocolate.