This is a little cheap, I know, but I'm just going to include the link here to these burgers:
Pioneer Woman's Favorite Burger. But please be assured they are worth the effort to make, even if I didn't take the time to document them in pictures, or write out the recipe.
The recipe has a great trick for caramelizing red onions, as well as spicing up some mayo and meat. I went with 1/2 lb burgers, instead of the admittedly daunting 1 lber like the recipe says, but basically stayed true to the recipe the rest of the way. The bite of the blue cheese with the sweet of the onions is pretty phenomenal.