1. Preheat the oven to 350*
2. Grease a 9x13 casserole dish
3. Cook the pasta according to the package directions, rinse and drain well
4. In a saucepan melt the butter and whisk in the flour, let cook for one minute while continuing to whisk
5. While whisking the flour, add in the milk, whisking continuously
6. Cook until thickened
7. Remove from the heat and stir in garlic powder, Sour Cream, dijon mustard and salt and pepper if desired
8. Pour the sauce over the pasta in the prepared baking dish
9. Add in the sauerkraut, green onions, kielbasa and 2 cups of the shredded Swiss Cheese
10. Stir to combine all
11. Top with the remaining Shredded Swiss Cheese
12. Place in the oven and bake for 35 to 40 minutes. The cheese should be browned and bubbly
13. Let rest for 5 minutes, then serve and enjoy!