Layer cookies between sheets of waxed paper in an airtight container; cover. Store at room temperature for up to 3 days or freeze for up to 3 months.
To make Quick Vanilla Sugar, split 1 vanilla bean in half lengthwise with a small sharp knife. Using the tip of the knife, scrape seeds from vanilla bean. Working in batches, in a food processor combine 4 cups sugar and vanilla seeds. Cover and process until combined. Transfer to a sterilized 1-quart jar; secure lid. Use immediately or store in a cool dry place indefinitely.