In a 13x 9 baking pan, spread cauliflower pieces. Drizzle with oil, sprinkle with salt and pepper. Toss to coat. Bake in preheated 400 degree oven until cauliflower starts to brown in places. Remove and reserve.
In a large pot, heat the oil over medium heat. Add shallots and onion and sauté until they begin to brown and caramelize around the edges. Add the garlic and sauté 1-2 min more. Add the wine and reduce by ½. Add cauliflower and stock. Bring to simmer. Puree with an immersion blender. Add cream but do not boil at this point. Taste for salt and pepper.
Ladle into bowls and garnish with dill.
Note: more stock or cream can be added to adjust thickness of soup.