Make sure that your butter and egg have time to warm to nearly room temperature. Line two cookie sheets with parchment paper. Preheat the oven to 375°F.

Whisk the flour, baking powder, baking soda, and salt together in a bowl.

Using a stand mixer with a paddle attachment, beat the butter on medium speed until it is slightly fluffy. Scrape the bowl and paddle attachment halfway through.

Add the sugars to the butter and beat on medium speed until lightened and fluffy (about 5 minutes). Scrape the bowl and the paddle attachment halfway through.

Add the egg and beat another 4 to 5 minutes. Add the vanilla and beat again until well incorporated.

Add about half the flour mixture to the butter mixture and stir with a spoon until nearly incorporated. Add the remaining flour and mix again. Do not overmix.

Add the chocolate and mix gently until everything is well distributed.

Scoop about 2 Tablespoons of dough into balls and place them onto the prepared cookie sheets, spacing them about 2 inches apart.

Bake the cookies in the preheated oven for 9 to 12 minutes. Start checking them at 9 minutes. The cookies should be very lightly browned on their tops and edges. Do not overbake!

As soon as they come out of the oven, sprinkle them with a little bit of sea salt towards the middle of the cookie. This helps to balance out the sweetness of the cookie.

Let the cookies cool for about 2 to 3 minutes on the cookie sheets. Transfer them to a sealed container and store at room temperature.