It’s hard to decide what’s best about this cookie. The texture’s a definite attention-grabber: It has a slight flakiness at first and then it’s all melt. The flavors of the rosemary and Parmesan, one of those meant-to-be matches, are front and center. The taste of Parmesan is often described as having a nutty quality, so including nuts seemed natural. But when I hit on pecans, everything changed, and the cookies took that magical leap into sublimity. They are a perfect match for white wine and champagne.
For the crumbliest texture — a good thing here — the cheese should not be very finely grated.
A word on the nuts: When I began making these, I used toasted almonds, and the cookies were very, very good. If almonds are what you’ve got, use them. You won’t be disappointed.
Working in a small bowl, rub the sugar and chopped rosemary together with your fingertips until the sugar is moist and aromatic and maybe even tinged with green. Put the flour, pecans, Parmesan, salt and rosemary-sugar in a food processor and pulse to blend. Drop in the pieces of cold butter and pulse until the mixture turns crumbly. Add the beaten yolk a little at a time, pulsing as each bit goes in, then continue to pulse until you have a moist dough that forms clumps and curds.
Turn the dough out and divide it in half. Pat each half into a disk.
Working with one disk at a time, place the dough between two pieces of parchment paper and roll to a thickness of 1/4 inch. Slide the dough, still between the paper, onto a baking sheet — you can stack the slabs — and freeze for at least 1 hour.
Getting ready to bake: Center a rack in the oven and preheat it to 350°F. Line a baking sheet with parchment paper or a silicone baking mat. Have a 1½-inch-diameter cookie cutter at hand.
Working with one piece of dough at a time, peel away the top and bottom papers and return the dough to one piece of paper. Cut out as many cookies as you can and put them on the lined sheet, leaving about an inch between them. Gather the scraps, then combine them with the scraps you get from the second sheet of dough, re-roll, freeze, cut and bake.
Bake the cookies for about 15 minutes, rotating the baking sheet at the midway mark, or until they’re golden and set. Let the cookies rest on the baking sheet for 3 minutes, then transfer them to a rack to cool completely.
Repeat with the remaining dough, always making certain that you start with a cool baking sheet.
Storing: The rolled-out dough can be wrapped well and frozen for up to 2 months; cut and bake directly from the freezer. The baked cookies can be kept in a covered container for up to 1 week at room temperature