Preparation - In a pot or a large saucepan, bring water to a boil. Add cauliflower and potatoes and simmer for 10 minutes, then set aside. Melt butter in a skillet. Add onion and garlic and saute just until onion in barely tender. Add to the cauliflower/potato mixture. Stir in the chicken broth and seasonings and bring to a boil. Reduce heat and simmer for about 3 or 4 minutes. Remove from heat and allow to cool for about 20 minutes. Pour mixture into a blender or food processor and puree until smooth. Return to pan. Stir in the half & half and milk. Mix well, then simmer for about 5 minutes. Serve piping hot. Top individual servings with shredded cheddar cheese.