2 cups (about 6 1/2 oz.) sliced cremini mushrooms
2 cups peeled, cubed butternut squash
2 cups (about 12 oz.) precooked polenta, cut into 1-inch cubes
3 tablespoons olive oil
Salt and pepper
1 pound (about 6 links) mild Italian pork sausage
1 teaspoon chopped fresh rosemary

Heat the oven to 425 degrees with a rack in the center position. Toss together the first four ingredients on a rimmed baking sheet and season with salt and pepper. Spread the mixture evenly. Use a fork to prick each sausage a few times, then tuck them among the other ingredients. Sprinkle on the rosemary. Bake until the sausages are cooked and nicely browned, stirring halfway through, about 30 minutes.