Patty Melts

This may be obvious to many people, but patty melts are great!  I'd never had one before and was pleasantly surprised by how simple and delicious they are.  It's not a particularly healthy choice, since it's basically a burger crossed with a grilled cheese sandwich, but it really hits the spot. 

All you need is:
Ground beef
Rye bread
Swiss cheese
Onions
Butter