In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy, about 3-4 minutes.

Add the egg and vanilla extract, mixing until well combined.

In a separate bowl, whisk together the flour, baking powder, and sea salt.

Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Chill the dough in the refrigerator for at least 30 minutes to make it easier to handle.

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

Scoop tablespoon-sized portions of dough and roll them into balls. Place them on the prepared baking sheet, spacing them about 2 inches apart.

Flatten each ball slightly with the palm of your hand and sprinkle a pinch of flaky sea salt on top.

Bake for 12-15 minutes or until the edges are lightly golden.

Remove from the oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.