Heat oven to 450. Lightly spray a 9" x 13" casserole baking dish w/ cooking spray. Place garlic bread, open-faced on a baking sheet and bake 12 mins. Remove from oven and let cool.
reduce oven heat to 350. Once bread is cooled, cut it into 1"- cubes and place cubes in casserole dish. Heat oil in lg skillet, over high heat. Add peppers, onions, salt and pepper.
Saute constantly until tender. Drizzle 1/2 the cheese sauce, or sprinkle 1/2 the shredded cheese over garlic bread cubes. Layer the beef strips and veggies over cheese. Cover the whole thing w/ foil. bake for 15 mins. Remove foil and top w/ remaining cheese. Bake 5 mins more.