In a medium pot, heat a drizzle of oil over medium-high heat and sauté the onion for 4–5 minutes, until soft. Add the garlic and cook for another minute.
Add the parsnips, pear (or apple), thyme, and stock along with 2 cups of water and bring to a simmer. Cook for 20–30 minutes, until the parsnips are very soft.
Add the cream, season with salt and pepper, and purée the soup right in the pot with a hand-held immersion blender, or carefully transfer it in batches to a blender to purée until smooth. Serves 4–6.