Cook spaghetti until tender, drain.
In a skillet, brown beef and onion in the butter.
Add flour, seasoning, and milk.
Cook until thick,
Mix one-half cup cheese with spaghetti.
Place half spaghetti and cheese mixture in baking dish.
Spread meat mixture on top of spaghetti in baking dish.
Top with rest of spaghetti.
Sprinkle with remaining cheese. Bake at 350 for 30 minutes.