1/2 teaspoon cream of tartar
3 lb. (about 8 medium) russet potatoes, peeled, sliced
1 (10 3/4-oz.) can condensed golden mushroom soup
1/2 cup water
1/4 cup all-purpose flour
3 tablespoons butter or margarine, melted
1/2 teaspoon salt
1/4 teaspoon pepper
1/4 teaspoon garlic powder
1 1/3 oz. (1/3 cup) shredded fresh Parmesan cheese, if desired
1) In large bowl, combine 1 cup water and cream of tartar. Add sliced potatoes; toss to coat. Drain, discarding water. Place potatoes in 3 to 4-quart slow cooker.
2) In medium bowl, combine soup, 1/2 cup water, flour, butter, salt, pepper and garlic powder; mix well. Pour mixture over potatoes; stir gently to coat.
3) Cover; cook on Low setting for 5 to 6 hours.
4) Just before serving, sprinkle Parmesan cheese over top.