14tablespoonsunsalted butter, 1 3/4 sticks, softened but still cool, about 65 degrees
1cupgranulated sugar, 7 ounces
1/4cuppacked light brown sugar, 1 3/4 ounces
2cupsold-fashioned rolled oats
1 ½cupssweetened flaked coconut
Preheat the oven to 350°F. Line 3 cookie sheets with parchment paper.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt; set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugars 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. Scrape down bowl and add the egg and vanilla and beat on medium-low until fully incorporated, about 30 seconds. Scrape down bowl again. With mixer running at low speed, add flour mixture and mix until just incorporated and smooth, 10 seconds. With mixer still running on low, gradually add oats and coconut and mix until well incorporated, 20 seconds. Give dough final stir with rubber spatula to ensure that no flour pockets remain and ingredients are evenly distributed.
Divide dough into 24 equal portions (about 2 tablespoons each), then roll into balls. Place cookies on prepared baking sheets, spacing them about 2 ½ inches apart, 8 dough balls per baking sheet. Using fingertips, gently press each dough ball to 3/4-inch thickness.
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. Transfer baking sheet to wire rack; cool cookies completely on sheet.