Preheat oven to 375F.
Cook manicotti shells according to directions, drain, set aside
Heat oil over medium heat, saute garlic, onion, and eggplant until starting to brown. Add water, simmer until tender (approximately 10 minutes)
In medium bowl, stir together ricotta, bread crumbs, eggs, Italian seasoning, salt, and npepper. Mix in eggplant mixture
Spread a layer of spaghetti sauce with mozzarella sprinkled on top in the bottom of a 9"x13" pan/casserole dish
Put the filling in a zipper bag and cut off a corner. Pipe into the shells
Arrange the filled manicotti in the baking dish on top of the sauce/cheese. Top with the remaining sauce and cheese
Cover dish with foil and bake for 25 minutes. Uncover and bake another 10-15 minutes until bubbly.