Make tomato sauce (see below). Pour tomato sauce in a 9’’ cast iron skillet or oven-proof dish (about 2’’-3’’ deep). If using chicken sausage, add into sauce now.
Preheat oven to 375.
In a medium bowl, combine ricotta, 2 tablespoons shredded mozzarella (give or take- feel free to eyeball), 1/4 teaspoon salt, black pepper and fresh herbs.
Slice zucchini thinly with a vegetable peeler or mandolin. Place on paper towel and blot to remove any excess moisture.
Lay down two zucchini slices, slightly overlapping each other, flat on a cutting board. Add about a heaping tablespoon of ricotta mixture to one end (leaving a bit of space on the end). Roll up ricotta in zucchini. Place the wrap seam side down in sauce. Repeat for remaining zucchini slices.
If you have any leftover ricotta, place spoonfuls on top of the sauce.
Sprinkle top with remaining (almost 1/2 cup) mozzarella on top.
Place skillet in oven and bake until cheese has fully melted and zucchini is lightly tender, about 10- 15 minutes.
In a medium sauce pot, add in olive oil, onion and garlic. Saute until onion is translucent and just beginning to brown.
Stir in tomato paste and saute until dark in red color, about 2 minutes.
Add whole peeled tomatoes (as you add, crush them with your hands- be careful the juices will squirt out!), remaining juices, and the tomato puree. Season with salt and pepper.
Simmer for 20-30 minutes, until sauce has thickened.