Preheat your oven to 400°F.
Line a large sheet pan with parchment paper or foil for easier cleanup.
Add the sliced smoked sausage and frozen Normandy vegetables directly onto the prepared sheet pan.
Drizzle everything with olive oil, then sprinkle with garlic powder, Italian seasoning, salt, and pepper.
Toss everything together right on the pan until evenly coated. Spread into a single layer so the vegetables roast instead of steam.
Bake for 15 minutes, then remove the pan from the oven and stir or flip the sausage and vegetables.
Return to the oven and bake for another 10–15 minutes, or until the vegetables are tender and slightly caramelized and the sausage is browned around the edges.
Sprinkle with grated Parmesan cheese if desired and serve immediately.