In the bowl of a stand mixer fitted with the paddle attachment, add the granulated sugar, light brown sugar, and finely grated fresh lemon peel. Use your fingers to massage the lemon zest into the sugars for about 20 seconds. This step helps elevate the lemon flavor in the finished cookies.

Add the softened unsalted butter to the sugar and lemon mixture. Mix on medium-high speed until light and fluffy, about 3 minutes. Stop the mixer and scrape down the sides of the bowl with a spatula. Add the egg and vanilla extract. Mix on low speed to combine well, then scrape down the bowl again. I always make sure my egg is at room temperature so it blends evenly into the dough.

In a separate bowl, whisk together the all-purpose flour, baking soda, cream of tartar, and kosher salt. Add these dry ingredients to the wet mixture in the stand mixer and mix on low speed until just incorporated. Do not over mix—the dough can have a few streaks of flour remaining.

Remove the bowl from the mixer and use a large spatula to gently fold in the chopped freeze-dried blueberries. Be careful not to over mix. Chill the dough uncovered for 30 minutes to let the flavors meld and the dough firm up, which makes for thicker, chewier cookies.

Preheat your oven to 350°F (175°C). Pour the coarse sanding sugar into a small bowl and line two baking sheets with parchment paper. Use a medium cookie scoop to portion out the chilled dough, then roll each portion into a ball. Roll each dough ball in the bowl of sanding sugar until fully coated, then place them 2 to 3 inches apart on the prepared sheets.

Bake the cookies on the center rack of the preheated oven for 8 to 9 minutes, or until the edges are set and slightly golden and the centers are puffy. Let the cookies cool on the baking sheets for 5 to 10 minutes, then transfer them to a wire rack to cool completely. Sprinkle the tops with extra sanding sugar for a crunchy finish if desired. I like to wait until the cookies are just warm before adding the extra sugar—it sticks better this way!