Preheat the oven to 400ºF.

Peel the sweet potato and cut into 1-inch pieces.  Cut the bell peppers into 1-inch pieces, and cut the onion into chunks. Mince the garlic.

Place all of the vegetables on a large sheet pan. Sprinkle with the garlic powder, salt, pepper, and rosemary. Drizzle the olive oil over the top, then stir to coat the vegetables with the oil and the spices.

Place the sausages on the sheet pan, nestled into the vegetables. Score each sausage diagonally 4 or 5 times with a sharp knife. This allows the juice to spill from the sausage to the pan, flavoring the vegetables as well.

Roast in the oven for 40 minutes, or until the sweet potatoes are tender and the sausages are cooked through (when an instant read thermometer reaches 160ºF). Turn the oven to broil and broil for 2-3 minutes to crisp the vegetables, watching closely to make sure they don’t burn.

Serve with mixed greens, if desired.