Preheat the oven to 400°F (200°C).
Line a large baking sheet with parchment paper for easier cleanup (optional).
In a mixing bowl, combine the bell peppers, red onion, and baby potatoes. Drizzle with the olive oil, garlic powder, Italian seasoning, salt, and pepper. Toss to coat the vegetables evenly.
Arrange the seasoned vegetables on one side of the baking sheet.
Place the sausages on the other side of the baking sheet, leaving space between them and the vegetables.
Bake in the preheated oven for 25-30 minutes or until the sausages are cooked through and the vegetables are tender and slightly caramelized, stirring halfway through for even cooking.
Once done, remove from the oven and let it cool for a couple of minutes. Garnish with fresh parsley if desired.
Serve hot and enjoy your easy sheet pan sausage dinner!