3 ounces (6 tablespoons) unsalted butter, softened, plus more for tins
3 large eggs
1 cup sugar
1 teaspoon pure vanilla extract
Pastry Cream (recipe below)
Chocolate-Ganache Glaze (recipe below)
Preheat oven to 350 degrees. Butter and flour standard muffin tins. Whisk together flour, baking powder, and salt in a small bowl. Warm milk and butter in a saucepan over low heat.
Beat eggs and sugar with a mixer on high speed until thick and pale, about 5 minutes. Beat in dry ingredients.
Bring milk and butter to a boil. With mixer on low speed, add milk mixture to batter, and beat until smooth. Add vanilla. Divide batter among muffin cups, filling each halfway. Bake cupcakes until light gold, about 15 minutes. Let cool in tins for 10 minutes, then transfer to wire racks. Let cool.
Using a serrated knife, cut each in half horizontally. Spread 1 tablespoon vanilla cream on each cupcake bottom. Sandwich with top. Spoon glaze over each, and serve immediately.
Pastry Cream Ingredients
2 cups milk
1/2 cup sugar
4 large egg yolks
2 teaspoons pure vanilla extract
Pinch of salt
6 tablespoons cornstarch
In a medium saucepan, combine milk and 1/4 cup sugar over medium heat, and bring to a simmer. Meanwhile, in a medium bowl, whisk egg yolks and remaining sugar until well combined. Whisk in vanilla and salt. Whisk in cornstarch, 1 tablespoon at a time, until fully incorporated. While whisking egg mixture constantly, slowly add 1 cup of the heated milk to the egg mixture. Strain this mixture into milk remaining in saucepan. Continue cooking over medium heat, whisking constantly, until mixture comes to a full boil, 4 to 6 minutes.
Transfer to a medium bowl, and cover with plastic wrap, pressing wrap against the filling to prevent a skin from forming. Refrigerate until at least 3 hours and up to overnight.
Chocolate-Ganache Glaze Ingredients
2/3 cup heavy cream
6 ounces semisweet chocolate, finely chopped
1 tablespoon light corn syrup
Bring cream to a boil in a small saucepan. Remove from heat, and add chocolate and corn syrup. Let stand for 5 minutes. Whisk until smooth. Transfer to a bowl, and let cool, stirring often. Use immediately.