PREPARE THE COOKIE DOUGH

1. Whisk together the gluten-free 1:1 flour, baking powder, baking soda, and salt. Set aside.
2. Using an electric hand mixer or a stand mixer with the paddle attachment, cream together the butter, granulated sugar, and light brown sugar for ~2 minutes, until light and fluffy, scraping down the sides and bottom of the bowl as needed.
3. Add the peanut butter and mix until well combined.
4. Add the egg, egg yolk, and vanilla extract and mix until smooth and combined.
5. Add the dry ingredients and mix on low speed just until combined and no flour streaks remain, scraping down the sides and bottom of the bowl as needed.
6. Cover the bowl and chill the dough in the refrigerator for at least 1–2 hours. The dough may still feel slightly soft after chilling.

BAKE THE COOKIES

1. When ready to bake, preheat the oven to 350°F (177°C) and line a large baking sheet with parchment paper. For best results, bake one tray at a time with 6 cookies per tray.
2. Place the 1/3 cup granulated sugar in a small bowl. Using a medium cookie scoop, portion the dough into balls, about 2 tablespoons (40 g) each. Roll each portion between your palms until smooth, then roll in the granulated sugar to evenly coat.
3. Arrange 6 dough balls on the prepared baking sheet, leaving space between each cookie. Using a fork, gently press down on each ball in one direction, then again in the opposite direction to slightly flatten the dough and create a crosshatch pattern.
4. Bake on the center rack for 9–11 minutes, or until the edges are set and lightly golden. The centers should still look slightly underdone and will continue to set as the cookies cool.
5. Immediately after removing the cookies from the oven, place a large round cookie cutter or bowl slightly larger than a cookie around each one and gently swirl it in a circular motion to smooth the edges and create a round shape.
6. Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Store the cookies in an airtight container for 4-5 days.