Cook cauliflower in 1 cup water until tender. Drain. Reserve liquid and 1 cup cauliflower. In blender, blend rest of cauliflower and the reserved liquid. Set aside. In large saucepan, cook onion in margarine. Stir in flour. Gradually, add 1 cup water and bouillon cubes. Stir until thickens. Stir in mashed cauliflower, reserved flowerets and cheese. Cook until cheese melts. Add milk and nutmeg. Heat through.