Make the Cookies:

1. Preheat oven to 350°F (175°C) and line baking sheets with parchment paper.
2. In a large mixing bowl, cream the butter and sugar together until light and fluffy. Add the egg and vanilla extract, mixing until combined.
3. In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until a dough forms.
4. Scoop out 1.5-tablespoon portions of dough, roll into balls, and flatten slightly with the palm of your hand. Place on the prepared baking sheets about 2 inches apart.
5. Bake for 8–10 minutes, or until the edges are set and the cookies are lightly golden. Let the cookies cool completely on a wire rack.

Make the Topping:

1. In a medium saucepan, heat the heavy cream over medium heat until just simmering.
2. In a bowl, whisk together the sugar and egg yolks until pale and creamy. Slowly pour the hot cream into the yolk mixture, whisking constantly to prevent curdling.
3. Return the mixture to the saucepan and cook over low heat, stirring constantly, until it thickens enough to coat the back of a spoon (about 5–7 minutes). Stir in vanilla extract and let it cool completely.

Assemble the Cookies:

1. Spoon or pipe a dollop of the cooled custard onto the center of each cookie, spreading slightly.
2. Sprinkle a thin layer of granulated sugar over the custard. Use a kitchen torch to caramelize the sugar until golden and crisp. Allow the topping to cool and harden before serving