1/2 shredded cheese, I used Brick
1 tsp of grainy mustard
1/2 tsp of grated lemon rind
Prepare the béchamel, add the mustard
When you get desired thickness, add cheese and keep stirring.
Add spaghetti and stir to warm throughly
Sprinkle lemon rind on top and enjoy.
It might sound out of place to put lemon rind, but I've done this before and was pleasantly surprised.