Preheat oven to 400°F and spray a large sheet pan with cooking spray.
In a large bowl, combine potatoes, broccoli, bell peppers, and onion.
Drizzle vegetables with olive oil and sprinkle with Italian seasoning, garlic powder, salt, and pepper, tossing to coat evenly.
Spread vegetables in a single layer on the sheet pan and nestle sausage slices throughout.
Roast for 30-35 minutes, stirring halfway through, until potatoes are tender and vegetables are caramelized.
Serve hot with your favorite dipping sauce or mustard on the side.