In a large saucepan, melt butter over medium heat.

Add onions and saute for about five minutes, until tender.

Add flour, stirring until completely combined. Cook for one minute, then add the chicken broth and milk.

Turn heat to medium high, then cook stirring often until broth begins to thicken.

Reduce heat to medium then add kielbasa, diced potatoes, sauerkraut and parsley. Simmer for five minutes, then add shredded cheddar.

Stir to combine and remove from heat. Serve sprinkled with black pepper.