How To make Speedy Cream Of Potato Soup

2 tablespoons butter or margarine
1 medium onion

chopped
4 1/2 cups water
1/2 teaspoon salt
dash pepper :

if desired 2 1/4 cups Betty Crocker Potato Buds Mashed
potato mix (dry) shredded cheddar cheese

if
chopped green onions :

if desired
Melt margarine in 2 qt saucepan over medium heat. Cook onion in margarine about 3 minutes, stirring occasionally, until tender. Stir in water, salt and pepper. Heat to boiling; remove from heat. Stir in potato mix until dissolved. Serve with cheese and onion tops.