Place patties in a single layer or stack and separate layers with non-greased freezer paper. Insert carefully into a freezer bag, lay flat in the freezer (if you have the room), and consume within three months.
Do not thaw the patties at room temperature. Instead, stick the patties in the refrigerator and wait until they are at least partially thawed. You can grill partially frozen patties, but it may take longer for the centers to finish. This could also result in an unevenly cooked burger.
Store hamburger patties the same way you’d store ground beef. Either keep the meat in its original container or wrap in saran wrap and insert into a plastic bag. The meat should stay fresh for one to two days.
Memorial Day
Transfer the baking sheets to wire racks until the eggplant is cool enough to handle, about 15 minutes. Chop the eggplant into rough cubes—you should have about 2 cups.
Process until the mixture is finely chopped and clumps when you squeeze a little of it in your hand. Taste and season with salt and pepper as needed. Add the egg and process until blended 
Arrange in a single layer on a parchment lined baking sheet, cover with plastic wrap, and refrigerate to firm the patties at least 1 hour and as long as overnight.
Cook until the burgers are heated through and browned, about 4 to 5 minutes per side. Lay a slice of cheese, if using, on each patty.
