First, make the cookie dough. In the bowl of a stand mixer fitted with the paddle attachment, combine the sugar and zest for the cookie dough. Use your fingers to rub the zest into the sugar—this will infuse the sugar with oils from the zest.
Mix the dry ingredients. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
Cream the butter and sugar. Add the Land O Lakes® Unsalted Butter to the sugar in the stand mixer bowl and beat on medium-high until light, fluffy, and doubled in volume, 2 to 3 minutes, using a rubber spatula to scrape down the bottom and sides of the bowl as necessary.
Add the egg, lemon flavoring, then the dry ingredients. Reduce the mixer to low, add the egg and lemon flavoring, and beat until just combined. Scrape down the bottom and sides of the bowl. With the mixer on low, gradually add the dry ingredients and beat until just combined. Scrape down the bottom and sides of the bowl once more and beat on low for an additional 30 seconds.
Prep the cookies for chilling, then chill for 1 hour. Use a 3-Tablespoon cookie dough scoop to portion the cookie dough into balls, lining them up next to each other on a parchment-lined sheet pan. Cover the pan loosely with plastic wrap and refrigerate for 1 hour.
Prep the oven and pans. After 1 hour, position a rack in the center of the oven and preheat the oven to 350°F. Line two half sheet pans with parchment paper.
Make the lemon sugar for the coating. In a medium, shallow bowl, combine the sugar and zest for the coating. Use your fingers to rub the zest into the sugar.
Coat the cookies. Remove the sheet pan of cookie dough from the refrigerator and discard the plastic wrap. Roll each cookie dough ball in the lemon sugar, covering them completely. Place the coated cookies at least 3 inches apart on the prepared sheet pans.
Bake the cookies. Bake one pan at a time for 10 minutes, or until the edges have set but the centers are still gooey. The cookies will look puffed when you pull them out of the oven, but will fall and crack into the perfect cookies as they cool. Cool the cookies on the pan on a wire rack for 20 minutes, or until the edges and bottoms of the cookies have set and feel firm to the touch. Repeat with the remaining cookie dough.
Serve and store. Serve warm or at room temperature. The cookies can be stored in an airtight container or zip-top bag at room temperature for up to 3 days.