Combine the cauliflower, stock, water, garlic powder, and onion powder in a large soup pot. Bring to a boil and simmer for 20-30 minutes, or until the cauliflower is tender. Blend in the pot with an immersion blender (or remove to a large blender and blend in batches then return to the pan) until smooth. Stir in the ham, and thyme leaves and simmer another 10 minutes. Add the butter and apple cider vinegar. Remove from the heat and season with salt and pepper to taste.Serve hot.