Preheat the oven to 375 degrees F.
Add the Brussels sprouts, parsnips, sweet potatoes and onions to a baking sheet. Add the olive oil, sage, salt and pepper and toss. Put the sausages in and around the vegetables.
Bake until the sausages are cooked through and the vegetables are tender, 40 to 45 minutes. Serve.
Recipe courtesy of Ree Drummond