Preheat oven to 350 degrees F.
Spray a 9x13 baking dish with cooking spray. Set aside.
Cook sausage until completely browned and cooked through. Drain juices. Set aside.
In a medium sauce pan, melt the butter over medium-high heat.
Add the onion and cook for 3 minutes.
Add the flour and cook for 2 more minutes.
Add the milk and stir constantly until sauce comes to a boil.
Add the Italian dressing mixes and the cream cheese and stir until smooth.
Remove from heat.
Layer ½ of the potatoes on the bottom of the baking dish.
Sprinkle ½ of the sausage evenly over the potatoes.
Spread ½ of the sauce evenly over the sausage.
Sprinkle 1 cup cheese evenly over the sauce.
Repeat the process.
Bake at 350 degrees F. for an hour to an hour and a half, or until the potatoes are done.
