In A Skillet, Brown Beef And Sausage; Drain. Place A Third Of The Onions And Peppers In A Slow Cooker; Top With Half Of The Meat Mixture. Repeat Layers Of Vegetables And Met, Then Top With Remaining Vegetables. Sprinkle With Salt, Pepper And Pepper Flakes. Cover And Cook On Low For 6 Hours Or Until Vegetables Are Tender. With A Slotted Spoon, Serve About 1 Cup Of Meat And Vegetables On Each Roll. Top With Cheese If Desired. Use Pan Juices For Dipping If Desired.