Prep Cauliflower: Remove core and leaves and cut into bite-size florets. Place on a large baking sheet and toss with 1 to 2 tablespoons olive oil, salt, and pepper.
Prep Garlic: Remove the outer most papery leaves from bulb of garlic, leaving the skin, and leaving them in a whole bulb bunch. Use a sharp knife to cut ¼ inch from the top of the cloves, to expose them. Drizzle 1 tablespoon olive oil right onto the exposed garlic cloves so it drips down inside the bulb of garlic. Place the whole bulb inside a piece of aluminum foil and seal closed. Place on baking sheet next to cauliflower.
Roast cauliflower and garlic at 400 degrees F for 30 minutes, tossing once halfway through cooking.
Make Soup: Melt butter in a large soup pot. Add onion and cook for 5 minutes. Add roasted cauliflower, and press the garlic cloves to squeeze the roasted garlic into the pot. Add chicken stock and thyme, cover, and cook for 15 minutes.
Blend: Ladle soup into a blender and blend until smooth. Return to pot. Add a little more stock, if it’s too thick. Stir in cream and nutmeg and season with additional salt and pepper, to taste.
Serve: Garnish soup with a pinch of cheddar cheese and chives. Serve with toasted crusty bread.
Notes
Make Ahead Instructions: Keep leftover cauliflower soup in an airtight container in the fridge for a few days.Freezing Instructions: Let cool completely then store in a freezer safe bag or container for up to 2 months. Let thaw overnight in the fridge.