Leek and Potato Soup

Cut leeks lengthwise, rinse, dry, then thinly slice crosswise. Melt butter in a skillet, add the onions, stir and cook under a cover of baking paper cut to the form of skillet on low heat for 5 minutes. Add cubed potatoes, add 1 ½ tbsp. water, bring to boil and cook on low heat for 15 minutes or until potatoes are tender. Mush, pour the milk and cream, warm without boiling, add salt and let stand, covered for 10 minutes. Serve, adding freshly ground white pepper.