Preheat oven to 400F. Grease a sheet pan with 1 tablespoon oil and set aside.
Slice zucchini into 1/8'' thick slices. Lay zucchini slices on grease sheet pan and oven roast for 10-12 minutes. Remove from oven and cool for 5 minutes before handling. Leave oven on for cooking the casserole.
While the zucchini is roasting, mix the ricotta cheese, parmesan cheese, 1/2 cup mozzarella cheese, 1 egg, and salt & pepper to taste. Stir just until combined.
In a 9x13 casserole dish, spread some homemade tomato sauce on the bottom.
Assemble zucchini roll ups by laying a zucchini strip on a flat surface and spread about 2 tablespoons of the ricotta mixture first over each individual zucchini strip. Top with a tablespoon os marinara sauce and a sprinkle of mozzarella cheese. Roll up and place in casserole dish. Repeat with remaining rolls. Drizzle remaining sauce (if any) on the rolls and sprinkle with remaining mozzarella cheese.
Bake uncovered for 20-25 minutes at 400F or until the cheese is melted and bubbly.