Thyme gives this hearty soup even more autumnal flavor.
In pot, cook parsnips, chopped fennel, 1/4 cup oil, garlic, shallots, and thyme over medium heat until vegetables are soft, about 10 minutes. Transfer to blender. Add stock; puree. Return soup to pot. Add milk. Heat soup over medium until heated through, about 5 minutes; season. Top with bacon, mushrooms, and fennel fronds. Drizzle with oil.