
With its velvety smooth cheese sauce and that signature salty, smoky flavor from the Kielbasa, this oven baked casserole is the grown-up version of classic mac and cheese with hot dogs. So much better!
Preheat oven to 375º.
Bring salted water to a boil and cook pasta until al dente. Drain and retiurn to the pot.
Slice sausage into ½ inch slices and add to a skillet with onions over medium heat. Cook until the sausages are browned and the onions are soft, about 5 minutes. Remove to a plate.
Warm milk and cream in the microwave.
In the same skillet, melt butter over medium-high heat. Whisk in flour, dry mustard and salt and pepper. Cook for about a minute. Gradually add warm milk mixture whisking until it sightly thickens and coats the back of a spoon. It will not be thick, about 3-5 minutes.
Remove from heat and add Worcestershire sauce and all but 1 cup of the cheese, whisking until smooth. Pour the sauce over the pasta and mix to coat. Stir in the sausages and onions.
Pour into a casserole dish and bake for 18-20 minutes until the cheese has melted and it is bubbly on the sides.