Preheat oven to 375.While the oven is preheating, place a medium to large cast-iron skillet on the stove over medium heat and warm up for about 5 minuets. In the skillet cook the sausage and onion until the sausage is fully cooked.
Add garlic and cook for about 1 more minuet.
Reduce heat to low and stir in marinara sauce, water, zucchini and spaghetti noodles.Make sure the noodles are mostly covered in liquid. (You don't need then fully cooked yet, they will finish cooking in the oven.) Turn off heat and cover with foil.
Baked in oven for 30 minuets.
Remove from oven and sprinkle with parmesan cheese. let sit for about 5 minuets before serving.
