2 c. water
1 tsp. cream of tartar
5 medium potatoes, thinly sliced
1/4 c. all-purpose flour (plain)
1 tsp. salt
1/8 tsp. pepper
1 1/2 c. milk
1 to 1 1/2 c. shredded cheese

Combine water and cream of tartar in large bowl; mix well. Add potatoes and stir well. (This will help keep the potatoes from darkening.) Drain. Turn potatoes into slow cooker.

In a saucepan, stir together flour, salt and pepper. Whisk in milk gradually until no lumps remain. Heat and stir until boiling and thickened. Stir in cheese to melt. Pour over potatoes. Cover and cook on low for 6 to 8 hours.