Kosher salt and freshly ground black pepper, to taste
PREPARATION
Preheat oven to 350°F and grease a 9×13-inch baking dish with butter or nonstick spray.
In a large pot of salted water, cook pasta according to package directions. Drain and set aside in a large bowl.
In a large saucepan, melt the butter over medium heat. Whisk in the flour and let cook 1 minute, stirring constantly.
Gradually whisk in milk, stirring constantly, and cook until thickened. Remove from heat, stir in garlic powder, Dijon mustard, and sour cream, and season with salt and pepper.
Pour sauce over pasta, and add the sauerkraut, sausage, green onions, and 2 cups of the cheese. Pour into prepared baking dish and top with remaining cheese.
Bake until golden brown and bubbly, 30-40 minutes. Let rest 5 minutes before serving. Enjoy!