Preheat broiler. Prepare rigatoni and spinach according to package directions.
Drain pasta, reserving 1/2 cup pasta water; return to pot. Add artichoke hearts, 1/2 cup mozzarella cheese, Parmesan cheese, salt, pepper and creamed spinach; toss to combine, adding reserved pasta water to thin as desired.
Transfer to a greased 2-qt. broiler-safe baking dish; sprinkle with remaining mozzarella cheese. Broil 4-6 in. from heat 2-3 minutes or until cheese is melted.