Preheat oven to 350 degrees and spray a 9x13 inch pan well with vegetable oil.
Heat oil in a frying pan over medium-high heat. Cook onions and garlic in oil until tender. Add mushrooms, and cook until soft. Remove from heat.
In a saucepan, combine spinach and 1/4 cup water. Cover, and cook over medium heat until wilted. Drain. In a large bowl, mix together spinach, onion/mushroom mixture, and ricotta cheese.
In a frying pan, brown moose meat over medium-high heat, stirring frequently. Once the meat is well browned, drain to remove excess grease. Stir in spaghetti sauce and water, and season with oregano, Italian seasoning, and salt and pepper.
Ladle enough of the meat sauce into a 9x13 inch baking dish to cover the bottom in a thin layer. Arrange a single layer of noodles over the sauce.
Spread one half of the ricotta cheese mixture over the noodles, and top with some of the spaghetti sauce and 1/4 cup of parmesan and 3/4 cup mozzarella cheese.
Repeat with remaining ingredients, ending with a generous layer of mozzarella cheese. Cover pan with aluminum foil.
Bake for 45 minutes, or until lasagna is hot and bubbly. Serve with garlic bread and a salad.