Preparation

• Combine the flour, cheese, lemon zest, pepper, and salt in a food processor. Process until combined. Add the butter and pulse until the dough resembles coarse crumbs. Add the sour cream and egg yolk and pulse again until just incorporated.
• Test the dough by squeezing a bit between your fingertips—if it’s too dry to hold together, sprinkle on a bit of lemon juice and pulse again. When the dough holds together, dump it onto a lightly floured surface and press into either a 12-inch log or a flat disk. Wrap in plastic and chill for 2 hours, or up to 2 days.
• Heat the oven to 375°F. For a dough log, slice it into coins just under 1/4 inch thick. For a disk, roll it out to just under 1/8 inch thick and stamp out 1-1/2- or 2-inch rounds or other shapes with a cookie cutter. Arrange them on an ungreased baking sheet and bake until well browned around the edges and no longer doughy in the center, 15 to 18 minutes for thinner coins, 20 to 22 minutes for thicker ones. Use a spatula to carefully transfer the coins to a cooling rack.

Make Ahead Tips

The coins will keep in an airtight container for two days.