An easy zucchini casserole recipe is Allrecipes's cheesy zucchini casserole that uses only six ingredients plus zucchini. This recipe takes about 20 minutes to prepare and serves around four people.
To make Allrecipes's cheesy zucchini casserole, pour 1/4 cup melted butter over 4 slices of bread cut into cubes. Mix in 2 cups cubed zucchini, 1 chopped onion, 1 teaspoon garlic salt and a beaten egg. Move the zucchini mixture to a 9-by-13-inch baking dish and top with 2 cups shredded cheddar cheese. Cover and bake the casserole for 30 minutes at 350 degrees Fahrenheit. Remove the cover, and bake the casserole for an additional 30 minutes.
For an Italian-style zucchini casserole, place 4 cups unpeeled, shredded zucchini into a strainer and sprinkle with 1/2 teaspoon salt. Let drain for 10 minutes, and then mix the zucchini with 2 eggs, 1/2 cup grated Parmesan cheese, 1/2 cup shredded cheddar cheese and 1 cup mozzarella cheese. Place in a greased 9-by-13-inch pan and bake at 400 degrees Fahrenheit for 20 minutes.
While the casserole is baking, cook 1 pound ground beef, 1 to 2 tablespoons minced garlic and a chopped onion, season with salt and pepper, and add in a 15-ounce can of tomato sauce. Spread the sauce over the zucchini mixture and top with 1/2 cup cheddar cheese and 1 cup mozzarella cheese. Bake for another 20 minutes at 400 degrees Fahrenheit.