via Taste of Home
Preheat oven to 350F / 180C.
Cook pasta, drain.
Meanwhile, in a large cast-iron skillet, melt butter over medium heat.
Stir in flour until smooth, cook 1 minute.
Gradually whisk in cream. Bring to a boil, stirring constantly. Cook, stirring, until thickened, 2 minutes.
Reduce heat, reserve 1 cup cheese and stir in remainder until melted.
Mix cheese and pasta (plus any optional ingredients) thoroughly, return to skillet. Top with remaining cheese, bake 20 minutes until crispy.