Shortbread makes a great holiday gift. This is excellent even without the lemon and rosemary, which I only started adding a couple of years ago to distinguish it from my mother's famous shortbread. (I tried it first with lavender, but my husband referred to that batch as "bubble-bath cookies.")
Makes 16 wedges.
Heat oven to 325° F. Cream together butter and sugar until fluffy, about 2 minutes. Mix in salt, rosemary, and lemon zest, then add flour and mix until batter starts to hold together and you don't see any dry patches, about 2 1/2 minutes.
Scrape the crumbly dough (knead for 30 seconds if it's too dry) into a 9-inch glass pie plate, then use your fingers to pat it down evenly. Prick holes all over the top with a fork, then use a sharp knife to score the shortbread into 16 skinny wedges.
Bake until nicely brown all over, 45 to 50 minutes, then remove from oven and cut immediately in the pan, retracing your lines with a sharp knife. Let cool completely in the pan.