Preheat oven to 350° degrees.
Wash & dry zucchini. Slice off both ends. Cut into slices lengthwise ⅛-¼" thick.
Lay out zucchini slices onto a baking sheet. Brush with olive oil and salt & pepper.
Bake for 11-12 minutes.
Pat the zucchini dry with paper towels.
Meanwhile, brown Italian sausage in a med-hot skillet. If using turkey sausage add a little olive oil as necessary. Break meat apart and cook until no longer pink.
Add onions and pepper. Cook and stir until softened, about 4 minutes. Add olive oil if needed. Set aside.
In a bowl mix the ricotta, eggs, oregano, basil, salt & pepper.
Spread a layer of marinara in an 11x13" baking dish.Then layer it all together. Layer two or three times...it doesn't matter.1. Zucchini2. Ricotta mixture3. Mozzarella4. Sausage onion mixture5. Marinara sauce**NOTE - I often lose track of the layers but not to worry! Just get it all in the pan and it will turn out lovely! Top with marinara and mozzarella cheese. Sprinkle with Parmesan.
Cover with foil and bake for 30 minutes.
Remove foil and return to oven for 10 minutes.If you like you can turn on the broiler for the last 5 minutes to brown the cheese a bit. Top with fresh basil or parsley.