Waste not, want not. "Compost cookies" demonstrate one approach to making good use of crumbly leftover bits and pieces: Bake them all together. For rainbow cookies, which are cut to size from what's essentially a sheet cake, the process is even simpler: Heap the colorful, chocolatey, almondy trimmings in see-through containers ($2) and stack them by the cash register. This was the last of the lot.
Mama Rao's Desserts & Pasta Fresca
6406 Eleventh Ave. (64th-65th Sts.), Dyker Heights, Brooklyn