1 1/2 cups all-purpose flour

1 teaspoon baking powder

1/2 teaspoon kosher salt

1/4 teaspoon baking soda

1/2 cup (1 stick) unsalted butter, room temperature

3/4 cup (packed) light brown sugar

1/2 cup sugar

1/4 cup powdered sugar

2 large egg yolks

1 large egg

1 teaspoon vanilla extract

8 ounces semisweet or bittersweet chocolate (do not exceed 72% cacao), coarsely chopped

Maldon or other flaky sea salt

Place racks in upper and lower thirds of oven and preheat to 375°.

Whisk flour, baking powder, kosher salt, and baking soda in a medium bowl; set aside.

Using an electric mixer on medium speed, beat butter, brown sugar, sugar, and powdered sugar until light and fluffy, 3-4 minutes.

Add egg yolks, egg, and vanilla.

Beat, occasionally scraping down the sides of the bowl, until mixture is pale and fluffy, 4-5 minutes.

Reduce mixer speed to low; slowly add dry ingredients, mixing just to blend.

Using a spatula, fold in chocolate.

Spoon rounded tablespoonfuls of cookie dough onto 2 parchment paper-lined baking sheets, spacing 1-inch apart.

Sprinkle cookies with sea salt.

Bake cookies, rotating sheets halfway through, until just golden brown around the edges, 10-12 minutes. The cookies will firm up as they cool.

Let cool slightly on baking sheets, then transfer to wire racks; let cool completely.

DO AHEAD - Cookies can be made 1 day ahead. Store airtight at room temperature.