Prepare all the vegetables as directed, making sure to slice everything into fairly even thicknesses. Place in a parchment-lined roasting pan.
Drizzle with with the olive oil. Bake for 20 to 30 minutes, stirring every 5 minutes or so. The vegetables should be tender on the inside and touched with golden brown on the outside.
Season gently with salt and pepper and the optional cinnamon and nutmeg. The veggies will have plenty of flavor of their own; no need to overdo it with seasonings.
Transfer to a covered serving container and keep warm until serving, then garnish with fresh rosemary and/or thyme leaves.