Preheat Oven to 400 degrees F.
Use a mandoline to slice zucchini lengthwise to create long, thin slices. Roughly 1/8 of an inch thick.
Place a few paper towels on the counter and lay strips of zucchini on paper towels. Sprinkle each side of zucchini with salt and let rest for 15-20 minutes. Remove excess moisture with a paper towel.
In a skillet, add sausage and brown. Drain excess grease.
To create the filling combine cooked sausage, parmesan, ricotta, egg, garlic and season with salt, pepper, and Italian seasoning, to taste.
Add marinara sauce to the bottom of the baking dish.
Spread about 1 tablespoon of filling on zucchini slice, add a small amount of mozzarella cheese, and roll it up. Place rolled zucchini in baking dish. Repeat with all zucchini slices.
Sprinkle the remaining mozzarella cheese over the top of the roll-ups.
Place into oven and cook for 25-30 minutes or until it is heated throughout and the cheese on top begins to brown.