Rinse the lemonbalm well and shake the excess water off, then allow to air dry completely. (A salad spinner speeds up the task). Fresh herbs should never be chopped when wet, so be sure the leaves are 100% dry after rinsing. Pick off the leaves and discard the stems, then pile the leaves on top of each other, a dozen at a time, and roll into a tight “cigar”. Using a sharp knife, slice very thinly. Pile the shredded herbs into a mound and chop them up a bit more, until quite fine. Use right away.

In a medium bowl, beat together the room temperature butter, chopped herb, fresh lemon zest, salt, and sugar until well mixed. Add the flour and mix well. You may need to use your hands for the final part of mixing. You can also use an electric mixer, just be sure not to overwork the dough after the flour has been added. Once the dough is smooth and coming together, roll it into a ball and flatten it. Wrap tightly in wax paper and chill for 20 minutes

Roll the flattened disc out on a lightly floured countertop and cut into shapes using a cookie cutter. Quick tip: shortbread dough can be a bit finicky to roll out (it can’t be too warm or too cool because of all that butter). So you can skip the whole rolling out step by shaping the ball of dough into a large cylinder shape, then cooling it in the fridge for 2 hours, and slicing about 1/4 inch thick. Place on a baking sheet lined with parchment paper, about 1 inch apart.

If you rolled the dough, refrigerate the unbaked cookies for 20 minutes before baking. This helps them hold their shape and bake more evenly.

Bake in a preheated 350 oven for 8 to 10 minutes on a rack placed in the top third of your oven. If your oven is on the hot side, check the cookies after 6 minutes to make sure they aren’t burning.