To the bowl of a stand mixer fitted with the paddle attachment (or large mixing bowl and electric mixer) combine the butter, sugars, egg, lemon extract, and beat on medium-high speed until creamed, light, fluffy, and well combined, about 4 minutes.: The bowl will gradually become lighter in color and the mixture should look airy, almost mousse like, as tiny air pockets from the butter and sugar form; you will hear a steady, smooth whirr from the mixer and feel the weight lighten when you lift the paddle. This aeration is critical because it yields a tender crumb and helps the cookies rise subtly while baking. A common mistake is under creaming, which yields dense cookies, or over creaming, which can introduce too much air and cause excessive spread. If the mixture seems curdled, scrape the sides and continue briefly on low to reincorporate.
Stop, scrape down the sides of the bowl, add the lemon zest, honey, optional food coloring, and beat on medium-high speed until well combined, about 2 minutes. I used 1 teaspoon gel food coloring; add drops or gel to desired shade. One teaspoon gel makes the batter quite yellow but it mellows slightly after adding the dry ingredients.: After scraping, the bright flecks of lemon zest will disperse and release oils, perfuming the batter with citrus; the sound of a slightly lighter, smoother mix indicates integration. The honey will add glossy sheen to the dough and a touch of chew, while gel food coloring (if used) deepens the visual appeal without thinning the batter. Be mindful not to over color and to stop mixing as soon as the ingredients are uniform, otherwise you risk breaking down the air structure created earlier. If streaks of zest remain, fold briefly by hand to avoid overworking the batter.
Stop, scrape down the sides of the bowl and add the flour, cornstarch, optional salt, and baking soda (keep the baking soda in a nice little mound rather than sprinkling it).: When the dry mix hits the wet base, the noise from the mixer softens and the dough begins to thicken; visually the batter changes from glossy to dough like, slightly tacky to the touch. The cornstarch is barely visible but it calms the structure, giving a fine, tender crumb, while the mound of baking soda ensures a localized reaction with the lemon juice later. A typical pitfall is adding all dry ingredients too aggressively and overmixing, which tightens the gluten and yields a tougher cookie. Use a low speed and stop when just incorporated to keep the texture soft.
Add the lemon juice directly on top of the baking soda. It will bubble and foam, which means the baking soda has been activated and this is good; if your soda doesn’t bubble it’s old and expired. Beat on low speed until just combined, about 1 minute.: As soon as the lemon juice hits the mound of baking soda , you should see a lively bubbling and foaming action, and you may catch a bright citrus aroma rising from the bowl; this indicates activation and helps the cookies gain gentle lift and a tender crumb. The immediate fizz is a visual cue that the chemical reaction is working, so if nothing happens the baking soda may be stale and should be replaced. Beat on low speed until just combined, about 1 minute, but avoid long mixing which can flatten the bubbliness important for texture.
Stop, scrape down the sides of the bowl, and using a large cookie scoop, 1/4-cup measure, or your hands, form approximately 12 equal-sized mounds of dough, roll into balls, and flatten slightly.: The dough will feel soft and slightly tacky, with yellow flecks from the lemon zest . You should notice a pleasant citrus perfume as you shape each mound, and flattening them a touch ensures even baking and that chewy edge to soft center contrast. An uneven scoop size leads to inconsistent bake times, so take care to make them equal; a common slip is making some too large which then bake unevenly.
Place mounds on a large plate or tray, cover with plastic wrap, and refrigerate for at least 3 hours, up to 5 days. Do not bake with unchilled dough because cookies will bake thinner, flatter, and be more prone to spreading.: The refrigerated dough will firm up and the butter will solidify, which reduces spreading in the oven and concentrates flavors. You will notice the dough becomes denser to the touch and the lemon aroma mellows and integrates with the sugars, yielding deeper flavor. Skipping chilling is a frequent error, resulting in flatter cookies that lose their signature soft center, so resist the urge to bake immediately.
Preheat oven to 350 F, line a baking sheet with a Silpat or spray with cooking spray. Place dough mounds on baking sheet, spaced at least 2 inches apart (I bake 8 cookies per sheet).: As the oven warms you may catch a warm, dry scent from the heating elements and your kitchen will start to feel cozy; setting it to 350 F ensures moderate heat that sets edges without overbrowning the tops. Lining with a Silpat or nonstick surface gives even heat transfer and prevents sticking. A mistake is crowding the pan; leave space so air circulates and the cookies bake evenly.
Bake for about 10 minutes, or until edges have set and tops are just set, even if slightly undercooked, pale, and glossy in the center; don’t overbake or undersides could become too browned. Cookies firm up as they cool.: Spacing prevents cookies from merging as they spread slightly, and you will hear a faint sizzle as the fat begins to soften during early bake minutes. The initial stage shows pale, glossy centers and edges just starting to set, which is the cue to avoid opening the oven too early. If placed too close, cookies can fuse and lose their shape, so allow adequate room.
Allow cookies to cool on baking sheet for about 10 minutes before serving. I let them cool on the baking sheet and don’t use a rack.: During baking you will notice a soft lemon scent, and the edges will turn from dough colored to a very light golden note while the centers remain slightly glossy; this is perfect because the cookies continue to firm as they cool. Overbaking dries them out and removes the soft chew, while underbaking too much leaves a raw center. Trust the visual cues more than the clock.
Optionally, dust with confectioners’ sugar. Or, for increased lemon intensity, make the lemon glaze and then sprinkle with additional lemon zest.: Cooling on the sheet lets residual heat finish the set up, and you will feel the texture change from fragile to pleasantly yielding as the centers stabilize. Moving them too soon can cause them to break, while leaving them too long on a hot tray may further brown the undersides. I prefer cooling on the sheet for a gently crisp edge and tender middle.
Optionally, dust with confectioners’ sugar. Or, for increased lemon intensity, make the lemon glaze and then sprinkle with additional lemon zest: A light dusting of confectioners’ sugar adds a delicate sweet finish, while a thin lemon glaze brings concentrated citrus and sheen; extra lemon zest on top boosts aroma. When glazing, watch for pooling which can soak the bottom, and if dusting, wait until completely cool to prevent melting.