Preheat the oven to 400°F (205°C) and line a sheet pan with parchment paper or foil.
In a large bowl, combine sliced smoked sausage, halved baby potatoes, sliced bell pepper, zucchini, and red onion.
Add olive oil, garlic powder, Italian seasoning, paprika, salt, and black pepper. Toss everything until well coated.
Spread the mixture evenly on the prepared sheet pan.
Bake for 25 to 30 minutes, flipping the ingredients halfway through cooking for even roasting.
If desired, sprinkle Parmesan cheese on top and broil for 2 minutes until melted and golden.
Serve hot, optionally over rice or pasta.