Bring a large pot of lightly salted water to a boil.Add the oil and the pasta and cook for 8 to 10 minutes or until al dente;drain well and return to cooking pot.
In a small saucepan over medium heat,melt 8 tablespoons butter;stir into the macaroni.In a large bowl,combine cheeses;mix well.
Preheat oven to 350 degrees F.
Add half and half,1 1/2 cups of cheese mixture,cubed processed cheese and eggs to macaroni;mix together and season with sodium-free salt and pepper.Transfer to a lightly greased deep 2 1/2 quart casserole dish.Sprinkle with the remaining 1/2 cup cheese mixture and 1 tablespoon butter.
Bake in preheated oven for 35 minutes or until hot and bubbling around the edges;serve.