Heat olive oil in a Dutch oven over medium heat. Saute onion, red pepper and mushrooms until tender, about 5 minutes. Stir in ground beef, salt, and pepper. Cook until beef is browned, about 5 to 7 minutes; drain.
Stir in pasta sauce, artichokes and spinach until well combined. Stir in cooked pasta. Transfer to a lightly greased 13"x9" baking pan; sprinkle with cheese.
Bake, uncovered, at 350° for 15 to 20 minutes or until heated through and cheese is melted.