Heat oven to 400ºF. Brown meat in large nonstick skillet; drain. Stir in the undrained tomatoes and the oregano; Cook 5 minutes or until heated through, stirring occasionally. Meanwhile, prepare the Kraft Macaroni as directed on package, omitting the butter. Add prepared Dinner to meat mixture; mix well and spoon into 9-inch square baking dish; top with cheddar. Bake 10 minutes or until cheddar is melted and casserole is heated through