Lastly, stir in the marinara, zucchini and spinach.
Cook briefly until the spinach is just wilted. Don't overcook the spinach. It's okay if the veggies are not fully cooked at this point. They will finish in the oven.
Final Assembly
Preheat oven to 400 F.
Set yourself up so you have all three portions of your lasagna set up assembly style with your casserole dish at the end.
Spray the casserole dish and lay down your first layer of noodles.
Layer on half of the meat filling and top that with a light coat of the cheese. (slightly less than 1/3)
Top with noodles and repeat the last of the meat filling and cheese, again using slightly less than a 1/3 of the cheese blend.
Finish with noodles on top and the rest of the cheese on top.
*See notes above on using foil now or later.
Bake for 40 minutes.
*Again, see notes above on foil for properly finishing off your lasagna.
Remove lasagna from oven and allow to cool a bit before cutting into it.
Serve with a green salad on the side for a complete meal.
Notes
Please note that the nutrition data given here is a ballpark figure. Exact data is not possible.