Preheat oven to 375°F and spread 1 cup marinara in a baking dish.
Brown ground chicken in a skillet until no pink; drain any liquid.
Mix chicken, spinach, ricotta, egg, Parmesan, Italian seasoning, salt, and pepper.
Lay a noodle flat and spread about 2–3 tbsp filling along one edge.
Roll the noodle tightly and place seam-side down in the dish.
Repeat with remaining noodles and filling.
Pour remaining marinara over roll-ups and sprinkle with remaining mozzarella.
Cover with foil and bake 25 minutes; uncover and bake 5 more minutes.