Large skillet cook bacon. Drain on paper towel, crumble and set aside. Keep the bacon grease. Cook onion in bacon grease until tender.

In large pan, mix onion, broth, and potatoes. Hear to a boiling then reduce heat to a summer cooking about 10 minutes until potatoes are tender.

Same skillet as bacon, melt butter over low heat. Stir in flour with whisk until smooth. Cook and stir 1 additional minute. Gradually stir in 2 cups of milk. Pour milk mixture into the potato mixture. Add remaining 2 cups of milk, salt, and pepper. Cook over medium heat, stirring constantly with whisk until mixture is thick and bubbly. add sour cream and cheese