Cook rotini according to directions on package. Drain.
Steam spinach until wilted, either in microwave or on the stove. Chop very fine.
In a large bowl, combine sour cream, eggs, parmesan, onion, diced tomatoes, cheese, oregano, salt and pepper and steamed spinach. Stir in rotini just until well coated.
Place mixture in slow cooker and cook on LOW for 4 hours. When there is 20 minutes left of cooking time, sprinkle with 1/4 c. cheddar jack and french fried onions.