Prepare the pastry cream according to your preferred recipe or use store-bought.

In a mixing bowl, cream together butter and sugar until light and fluffy, then add egg and combine well.

In another bowl, combine flour, baking powder, and salt; gradually add to wet ingredients until a soft dough forms.

Preheat the oven to 350°F (175°C). Scoop tablespoon-sized dough on a baking sheet, indent centers, and fill with pastry cream. Cover with additional dough and seal.

Chill cookies in the refrigerator for about 30 minutes to firm up.

Bake cookies for 12-15 minutes, until golden around the edges. Let cool on the baking sheet for a few minutes before transferring to a wire rack.

After cooling, sprinkle sugar on top of each cookie and use a kitchen torch to caramelize the sugar until golden brown.