Instructions
- 1. In food processor, process 1/2 cup sugar and 1 teaspoon lime zest until zest is evenly distributed, about 10 seconds; set aside.
- 2. Adjust oven racks to upper- and lower-middle positions; heat oven to 375 degrees. Line two large baking sheets with parchment paper. Whisk flour, baking powder, and salt in medium bowl; set aside.
- 3. In standing mixer fitted with paddle attachment or with hand mixer, beat butter, 1 cup granulated sugar, and brown sugar at medium speed until light and fluffy, about 3 minutes, scraping down sides of bowl with rubber spatula as needed. Add egg, remaining 2 teaspoons zest, and vanilla; beat at medium speed until combined, about 30 seconds. Add dry ingredients and beat at low speed until just combined, about 30 seconds, scraping down bowl as needed.