Spray a 9x13-inch casserole pan with cooking spray and set aside.

Cook and crumble sausage in a large skillet until meat is no longer pink; drain.

In the same skillet, add green onions and zucchini. Season with Italian seasoning, salt and pepper. Sauté until vegetables are tender. Stir in roasted bell peppers. Drain and cool. 

In a large bowl, combine the cooked sausage, the vegetable mixture, bread cubes, eggs and milk. Spread the mixture into the prepared pan. Top with cheese.

Cover and chill at least 8 hours or overnight.

Bake, covered, at 325°F for 1 hour or until cooked through and the casserole is hot and bubbly. Let stand 5 minutes before serving.