In a small pot melt butter on low heat. Whisk in flour and stir until well dispersed. Slowly whisk in milk always stirring and bring to a simmer. Add cheddar and seasoning. Cook on low until cheddar is melted completely. Do not boil, to prevent sauce from separating or scorching. Cook ravioli according to packaging instructions. Strain ravioli and gently toss in the sauce. Garnish ravioli with fresh scallions.