Preheat oven to 375˚F.
Spread cauliflower, parsnips, shallots, garlic, and thyme onto a baking sheet, in a single layer, and drizzle with oil. Sprinkle with cumin, paprika, salt and pepper and toss everything together until the vegetables are well coated with oil.
Roast vegetables for 25-30 minutes, tossing vegetables around 15 minutes into the roasting process.
Meanwhile pour stock into a medium pot and bring to a simmer. Lightly season with salt and pepper.
Once vegetables have roasted through and stock is hot, transfer both the vegetables and 2 1/2 cups stock into the well of a blender. Securely fasten the lib, but remove the small, plastic center-top and replace that with a kitchen towel with your hand securely over the towel (this will allow for the stream to escape without a soup ‘explosion’ occurring).
Puree mixture for 3 to 5 minutes or until the mixture is smooth. Add more stock and continue to puree if necessary.
Transfer the mixture into the pot that the stock was in and bring to a light simmer. Stir in sour cream or crème fraiche and adjust seasonings.
Top each bowl with a drizzle of extra virgin olive oil and fresh thyme leaves and serve.