For the neatest presentation, use a metal spatula or a butcher's scraper to remove the bars from the pan. Leftovers will keep for 2 or 3 days at room temperature, or for up to a week in the refrigerator. The cookie crust dough can be prepared up to 2 days in advance, then wrapped in plastic and stored in the refrigerator. When you're ready to bake the bars, simply bring the dough to room temperature and pat out as described above.