Philly Cheese Steak Casserole

3 cups uncooked wide egg noodles
1 lb. boneless sirloin steak, about 1/4 inch thick
1/4 teaspoon pepper
2 medium onions, chopped (1 cup)
1 small green bell pepper, chopped (1/2 cup)
1 can beef broth
1/4 cup flour
1/2 cup half & half
1 tablespoon Dijon mustard
3/4 cup shredded Cheddar cheese

Heat oven to 350º. Spray a 11x7 (2 quart) glass baking dish with cooking spray. Cook and drain noodles as directed on package. Meanwhile, remove fat from beef. Cut beef into 3/4" pieces. Heat a 12 inch nonstick skillet over medium heat. Cook beef seasoned with pepper, 2 to 3 minutes, stirring occasionally, until beef is brown. Stir in onions and bell pepper. Cook 2 minutes, stirring occasionally. Spoon into prepared baking dish.In a medium bowl, beat broth and flour with wire whisk until smooth. Add to skillet, heat to boiling. Cook, stirring constantly, until mixture thickens; remove from heat. Stir in half & half and mustard. Spoon over beef mixture. Stir in cooked noodles.Cover and bake 40 minutes Sprinkle with cheese, then bake uncovered, about 10 minutes more until cheese is melted and casserole is bubbly.