Line a large baking sheet with tin foil, and spray with cooking spray. Set aside.
Cut sausage into rounds. Chop the onions and potatoes the same size. This helps with cooking time.
Add the sausage rounds, onions, and potatoes into a large bowl. Drizzle with a tablespoon of olive oil and season with salt, pepper, and paprika. Toss together with your hands until everything is evenly distributed. Pour this out onto the sheet pan and spread out the sausage and potatoes.
Place into the heated oven and roast for 45 minutes to an hour, stirring every 15 minutes or so, until the potatoes are golden brown and tender. Turn off the oven.