Parmesan, egg, and garlic enrich the ricotta filling, so you don't need too much mozzarella on top.
Season eggplant with salt and pepper; arrange in a shallow 2-quart microwave- safe dish with a lid. Microwave on high until tender and pliable but not fully cooked, 6 to 8 minutes.
With a spatula, transfer eggplant slices from dish to a paper-towel-lined baking sheet, and arrange in a single layer. Blot dish dry, and spread bottom with 1/4 cup marinara sauce; set aside.
In a small bowl, mix together ricotta, Parmesan, egg, garlic, 1/4 teaspoon salt, and 1/8 teaspoon pepper. Pat eggplant dry with paper towels. Dividing evenly, spoon ricotta mixture onto the wide end of eggplant slices, leaving a 1-inch border on the wide end and a 1/4-inch border on either side. Starting at the wide end, roll up slices; arrange seam side down in a single layer in prepared dish. Top with remaining 3/4 cup marinara sauce.
Cover dish, and microwave on high until eggplant is very tender, 15 to 17 minutes. Sprinkle with mozzarella; microwave until cheese is melted, 2 to 3 minutes. Cool 5 minutes. Serve rollatini with bread, if desired, and garnished with more Parmesan.
Arranging the stuffed eggplant in a single layer ensures that each rollatini cooks through evenly.