Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a bowl, whisk together flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream together butter and ¾ cup granulated sugar until light and fluffy. Beat in the egg, lemon zest, and lemon juice until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until a soft dough forms. Chill dough for 15 minutes if sticky.

Scoop tablespoon-sized amounts of dough onto the prepared baking sheet. Use the back of a spoon to create a small indentation in the center of each cookie.

In a small bowl, whisk together heavy cream and vanilla extract. Spoon a small amount into each cookie indentation. Bake for 12-15 minutes, until edges are lightly golden.

Remove from oven and immediately sprinkle the tops with extra granulated sugar. Using a kitchen torch, carefully caramelize the sugar until golden and crackly. Allow to cool before serving.