1. Preheat oven to 400F. Coat baking sheet with cooking spray. Slice tomatoes lengthwise. Scrape out seeds with knife tip and discard seeds. Lay tomato halves cut side down on baking sheet. Scatter onion slices and garlic among tomatoes; sprinkle with black pepper to taste.
2. Trim ends off eggplant and cut length-wise into 8 slices. Lightly coat second baking sheet with cooking spray. Lay eggplant slices on sheet, overlapping slightly to fit. Coat eggplant slices lightly with cooking spray. Place both baking sheets in oven. Roast until eggplant slices are soft, and tomatoes puff and start to brown, about 15 min.
3. Meanwhile, in medium bowl, mix spinach, ricotta or cottage cheese, egg whites and herbs. When vegetables are doen, remove from oven; reduce heat to 350F. With tongs, pull skins off tomatoes, onion, and process until a chunky sauce forms.
4. Spoon 1 cup sauce into bottom of 9x9-baking pan. Place about 1/3 cup spinach-ricotta mixture on one eggplant slice; roll up from small end, and place seam side down in baking pan. Repeat with remaining slices, using all the filling. Top eggplant rolls with remaining tomato sauce, and sprinkle with Parmesan. Bake until cheese is melted and casserole is hot, about 25 min.