Make the Vanilla Pastry Cream
In a saucepan, heat the milk over medium-low until steaming.
In a bowl, whisk the egg yolks, sugar, salt, vanilla bean paste, and cornstarch until pale.
Slowly temper with hot milk, whisking constantly, then pour the mixture back into the saucepan.
Cook over medium-low for 8–12 minutes, whisking until thickened.
Remove from heat, stir in butter, and let chill with plastic wrap directly on the surface.

Prepare the Sugar Cookie Dough
Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper.
In a bowl, whisk flour, baking powder, and salt.
In a separate bowl, cream the butter and sugar until fluffy (about 2 minutes).
Add egg and vanilla; mix until light and combined.
Gradually add dry ingredients and mix just until combined.
Scoop dough into balls, roll in sugar, and gently flatten.

Bake the Cookies
Bake 6 cookies at a time for 9–10 minutes.
Let cool on the sheet for 5 minutes, then transfer to a wire rack.

Add Pastry Cream & Brûlée Topping
Once cooled, pipe chilled pastry cream onto each cookie.
Sprinkle about 1 teaspoon of sugar on top.
Use a kitchen torch to caramelize the sugar until golden and crackly.
Let the sugar crust cool for 10 minutes before serving.