Prep Vegetables: Wash and cut cauliflower into florets. Chop onion and mince garlic.
Sauté: Heat olive oil or butter in a large pot over medium heat. Add onion and garlic, cooking for 3–4 minutes until soft.
Cook Cauliflower: Add cauliflower florets and broth. Bring to a boil, then reduce heat and simmer for 15–20 minutes until cauliflower is tender.
Blend: Use an immersion blender to puree until smooth. (Or carefully blend in batches using a blender.)
Finish: Stir in milk, thyme (if using), salt, and pepper. Adjust seasoning to taste.
Serve: Garnish with parsley or chives and enjoy with crusty bread or croutons.