1Melt the butter in a large pot over medium heat. Saute the onion in the butter for 5 minutes. Stir in the cauliflower and potato and saute for 5 more minutes.
2Pour in the stock, bring to a boil, reduce heat to low and simmer for 20 minutes, or until all vegetables are tender. Add the milk, stirring well to blend. Season with salt and pepper to taste.