You'll need:
4 leftover matza balls
2 cups milk
2T butter
2T flour
1c grated cheese (we used comte, which is like gruyere, but a mix of cheeses is fine too)
1/4c parmesan
1 onion
1lb ground meat
5 cloves garlic
1T cumin
1/2t cinnamon
Preheat oven to 400 degrees.
Make a bechamel by melting the butter in a saucepan, whisking in the flour, letting it turn golden brown and then adding the milk slowly. Let it bubble til it's thick, and then whisk in the grated cheese.
In the meantime (probably while the bechamel is thickening), chop and saute the onion and add the meat, crushed garlic, and spices. Add salt and pepper and saute until meat is brown, working it into small bits as it cooks.
Pour meat into a small baking dish. Slice matza balls into 1/4 inch thick slices and place in one layer over meat. Pour bechamel over and top with parmesan. Bake until brown and bubbly, about 30 minutes.