Lori Jo's Zucchini Casserole

1 pound ground beef
potatoes
carrots
zucchini
1 can cream of chicken soup
milk
1/4 cup muenster cheese
1/4 cup Swiss cheese
1/2 cup extra sharp cheddar cheese
flour to thicken
extra cheeses for topping
Cheezits Crackers

Brown ground beef.  Add potatoes, carrots and zucchini.  Simmer 15 minutes in water to soften.  Make sauce of cream of chicken soup, 1 soup can of milk, and cheeses.  Use flour to thicken.  Layer ground beef in crockpot.  Add vegetables.  Top with sauce.  Sprinkle with 1 cup grated cheeses.  Crumble crackers and sprinkle on top.  Cook in crockpot until tender.