Preheat oven to 400°F. Line a rimmed baking sheet with parchment paper.
Place the sliced bell peppers and onions on the baking sheet. Drizzle the olive oil over the vegetables. Sprinkle on the Italian seasoning, salt and pepper and toss to evenly distribute the oil and seasonings.
Slice the sausages into ½-inch thick rounds and add them to the baking sheet with the peppers and onions. Spread everything out into an even layer on the baking sheet.
Bake for 30-35 minutes, tossing once halfway through the cook time, until sausage is browned and vegetables have softened.
Serve as is, or with pasta, rice, quinoa or in sandwich rolls.
