In a shallow medium bowl, combine 1/4 cup granulated sugar and 1 teaspoon citric acid. Whisk to combine. Add fresh zest from 1 medium-small Meyer lemon and use your fingers to rub the zest into the sugar and citric acid mixture until the sugar smells fragrant and the zest is incorporated throughout the mixture in small clumps. Set aside.

Center a rack in the oven and preheat to 350 (F). Prepare two sheet pans by lining with parchment paper sheets and set aside.

In a medium bowl, combine 2 3/4 cups all-purpose flour, 2 teaspoons cream of tartar, 1 teaspoon baking soda, and 1 teaspoon kosher salt. Whisk to combine and set aside.

Return to your mixer bowl and add 1 cup unsalted butter to the sugars and lemon zest from the 2nd step. Beat on medium-high speed for about 2 to 3 minutes, until light and fluffy. Reduce the mixer speed to its slowest setting and add 6 large egg yolks, one at a time, only adding the next egg yolk when the previous one is fully incorporated. Add 1 teaspoon fresh lemon extract. Once incorporated, stop the mixer and use a rubber spatula to scrape down the sides of the bowl. Turn the mixer back on to its lowest setting and gradually add the dry ingredients, beating on low speed until just combined.