Brown and drain ground beef. Chop spinach fine, grate 1/2 of 1 zucchini, mince garlic clove and add all three to beef. Add one jar spagehetti sauce and cook untill veggies are done. Add second jar and then turn off heat. Slice remaining zucchini lengthwise into 1/4 inch slices. Combine ricotta cheese, egg and parsley in a seperate bowl, set aside.
Preheat oven to 400 degrees. Pour about 2 cups of the sauce you have just prepared into the bottom of a 9x13 pan (I prefer a glass pan).
Layer 1/2 of the zucchini slices over sauce;.
Spread 1/2 of the ricotta mixture on zucchini slices;.
Sprinkle 1/2 of the mozzarella and parmesean cheeses over ricotta;.
Spread 2 cups sauce over this.
Repeat steps 3 - 6 using remaining ingredients.
Cover with foil and place on foil lined cookie sheet to catch any drips.
Bake 1 hour at 400 degrees. Can remove foil and cook an additional 10 minutes, if desired.