1. Preheat the oven to 400 degrees. Line a large baking sheet with foil and coat with cooking spray.
2. Put the potatoes, yams, brussels sprouts, onion chunks, and garlic cloves in a large bowl.
3. Lightly drizzle the vegetables with olive oil. Stir until they are all coated.
4. Season the vegetables with the fresh rosemary and salt and pepper. Stir again.
5. On the large baking sheet, add the vegetables. Make sure they are laid out flat. Place the baking sheet in the hot oven.
6. Roast vegetables for about 40-45 minutes, stirring them every 15 minutes or so. I like them a little crispy around the edges:)
7. I always remove the garlic cloves to serve, but if you want to eat them, go for it. Serve hot.