In a large bowl, combine the cooked and drained spinach, ricotta or cottage cheese, bread crumbs, lightly beaten eggs, mushrooms, and chopped green pepper.
Preheat the oven to 350°F.
Pour the spinach mixture into a buttered 13-inch baking dish and spread sour cream on top.
Pour a layer of spaghetti sauce over the sour cream, using most but not all of the sauce.
Cover the mixture with slices of mozzarella cheese.
Spread the remaining spaghetti sauce over the cheese slices.
Sprinkle basil and grated Parmesan cheese on top.
Bake for 30 minutes or until the dish is golden and bubbly.