Scalloped Potatoes with velveeta

8 medium russet potatoes 1 yellow onion , coarsely chopped 4 tablespoons butter 4 tablespoons all-purpose flour 3 cups milk 1 lb Velveeta cheese , cubed and[...]

4 1/2 lbs red potatoes, cut into 1/4-inch slices 16 ounces sour cream 3/4 lb Velveeta cheese , cubed 8 ounces chopped ham 1/2 cup green onion , slices 1/4 cup[...]