In a medium mixing bowl, cream together the softened butter and sugars. Add the egg and vanilla extract and stir until just combined.
Add the flour, baking powder, and salt. Stir until a dough ball begins to form. Then stir in the chocoalte chips.
Cover and chill in the refrigerator for one hour, and up to overnight.
Spoon onto a baking sheet lined with a baking mat or parchment paper. Top with flaky sea salt, optional.
Bake at 325°F for 8-10 minutes, just until the edges begin to brown.