Thin And Crispy Oatmeal Cookies

1. Adjust oven rack to middle position and heat oven to 350 degrees. Line 3 baking sheets with parchment paper. Whisk flour, baking powder, baking soda, and salt in medium bowl; set aside.
2. Using stand mixer fitted with paddle, beat butter, granulated sugar, and brown sugar at medium-low speed until just combined, about 20 seconds. Increase speed to medium and continue to beat until light and fluffy, about 1 minute longer, scraping down bowl as needed. Add egg and vanilla and beat on medium-low until fully incorporated, about 30 seconds, scraping down bowl as needed. Reduce speed to low, add flour mixture, and mix until just incorporated and smooth, about 10 seconds. With mixer still running on low, gradually add oats and mix until well incorporated, about 20 seconds. Give dough final stir to ensure that no flour pockets remain and ingredients are evenly distributed.
3. Working with 2 tablespoons of dough at a time, roll into balls and place 2-1⁄2 inches apart on prepared baking sheets. Using fingertips, gently press each dough ball to 3⁄4-inch thickness.
4. Bake 1 sheet at a time until cookies are deep golden brown, edges are crisp, and centers yield to slight pressure when pressed, 13 to 16 minutes, rotating baking sheet halfway through baking. Transfer baking sheet to wire rack and let cookies cool completely.

THIN AND CRISPY COCONUT-OATMEAL COOKIES
Decrease oats to 2 cups and add 1-1⁄2 cups sweetened flaked coconut to batter with oats in step 2.

THIN AND CRISPY ORANGE-ALMOND OATMEAL COOKIES
Beat 2 teaspoons grated orange zest with butter and sugars in step 2. Decrease oats to 2 cups and add 1 cup coarsely chopped toasted almonds to batter with oats in step 2.

SALTY THIN AND CRISPY OATMEAL COOKIES
Reduce amount of salt in dough to 1⁄4 teaspoon. Lightly sprinkle 1⁄2 teaspoon coarse sea salt evenly over flattened dough balls before baking.