In a frying pan, add 1 tablespoon butter and sauté onion, celery, and green beans until onions are translucent.
Add milk and butter to a small pot. Once butter has melted, add cheeses, salt, garlic powder, pepper and paprika. Mix 1 tablespoon cornstarch or arrowroot powder with 3 tablespoons water then add to cheese sauce to thicken.
Combine cheese sauce with sautéed vegetables and stir.
Boil water in a medium pot with a pinch of salt, add pasta and cook until desired firmness (5-8 minutes). Drain pasta.