Begin by preheating the oven to 325 degrees F. and greasing a 9x13” baking pan with a little zero-calorie nonstick cooking spray. Using a julienne tool or slicing carefully with a knife, create thin strips of zucchini (cutting lengthwise). Squeeze the excess moisture out by wrapping it up in a clean tea towel or cheese cloth and pressing firmly. Set aside. To prepare the meat sauce, begin by cooking ground beef in a large skillet over medium-high heat. After about 5 minutes, add diced green pepper, onion, tomato sauce, basil, oregano, and a little water based on desired thickness of sauce. Bring mixture to a boil, then reduce heat and simmer for about 20 minutes, stirring frequently. To assemble lasagna, spread 1/2 of the meat sauce into the bottom of the baking pan. Then, form a layer of zucchini slices followed by a layer of spinach and mushrooms. Repeat layers of meat sauce, zucchini slices, spinach and mushrooms until the ingredients have been completely used up. Bake in an oven for 45 minutes to an hour based on desired degree of doneness. Once ready, remove from oven and let stand for 5 minutes before serving.