1. For the filling: Bring the cream to a simmer in a medium saucepan over medium heat.

2. Meanwhile, whisk the egg yolks, sugar, and salt together in a medium bowl, then whisk in the cornstarch until pale yellow and thick, about 30 seconds.

3. Slowly whisk the hot cream into the egg mixture, then return the mixture to the saucepan and cook over medium heat, whisking constantly, until thick and glossy, 1-2 minutes.

4. Off the heat, whisk in the butter and vanilla.

5. Transfer the mixture to a small bowl and refrigerate until chilled and set, about 2 hours.

6. For the cupcakes: Adjust the rack to the middle position and preheat oven to 350°F. Grease and flour 12-cup muffin tin.

7. In the bowl of a stand mixer, whisk together the flour, sugar, baking powder, and salt.

8. On medium-low speed, beat the butter into the flour mixture, one piece at a time, about 30 seconds each. Continue to beat the mixture until it resembles moist crumbs, 1 to 3 minutes.

9. Beat in the eggs, one at a time, until combined about 30 seconds.

10. Beat in the milk and vanilla, then increase the mixture speed to medium and beat the batter until smooth, light, and fluffy, 1 to 3 minutes.

11. Fill the muffin tins ¾ full. Bake the cupcakes 18 to 20 minutes, until a toothpick inserted comes out with a few moist crumbs attached. Cool in the tins for 10 minutes, then transfer to a wire rack to cool completely.

12. For the glaze: Microwave all of the ingredients together, whisking often, until melted and smooth, 1 to 2 minutes. Let the glaze cool, uncovered until it is thickened but pourable, about 20 minutes.

13. To assemble: Cut the center from each cupcake, leaving the top intact, and fill with 2 tablespoons filling.

14. Trim and replace cupcake top and set on wire rack over a parchment-lined baking sheet.

15. Pour the glaze over the cupcakes, letting it run down the sides. Refrigerate until set, about 10 minutes.