Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a bowl, whisk together the flour, baking powder, and salt.

In a separate bowl, cream the butter and sugar until light and fluffy. Beat in the eggs, one at a time, then stir in the vanilla.

Gradually mix in the dry ingredients and milk, alternating between the two, starting and ending with the dry ingredients.

Fill the cupcake liners about 2/3 full with batter and bake for 18-20 minutes or until a toothpick inserted into the center comes out clean. Cool completely.

In a saucepan, heat the milk until it starts to simmer. In a bowl, whisk together the egg yolks, sugar, and cornstarch until smooth.

Gradually whisk some of the hot milk into the egg mixture to temper it, then pour the mixture back into the saucepan with the remaining milk.

Cook over medium heat, stirring constantly, until the mixture thickens and boils. Remove from heat and stir in the vanilla.

Transfer the custard to a bowl, cover with plastic wrap (pressing the wrap directly onto the surface of the custard to prevent a skin from forming), and chill until cool.

Place the chocolate chips in a bowl. Heat the cream in a saucepan until it just begins to simmer, then pour it over the chocolate. Let it sit for a few minutes, then stir until smooth. Cool to a spreadable consistency.

Once the cupcakes are cool, cut a small hole in the center of each cupcake and remove a piece of the cake to make room for the filling.

Spoon or pipe the custard filling into each cupcake.

Spread or pipe the chocolate ganache on top of each cupcake.

Once assembled, the Boston Cream Cupcakes are ready to serve. You can refrigerate them until ready to enjoy, letting them come to room temperature for a few minutes before serving.