In medium sauce pan combine buttermilk, milk and cream cheese. Over medium heat melt cream cheese into milk stirring constantly. (I use a whisk rather vigorously.).
When cheese is well melted add salt, pepper, onion powder and dill. Add lemon juice last slowly.
If you like your sauce a little thicker use 1/2 tbs of flour mixed into a slurry with a little of the sauce mixture so you don't get lumps.