I made the best grilled cheese sandwich I've ever eaten.
The process started by melting over medium heat a pat of butter on a square skillet pan, then threw on a good pinch of sliced red onions, moving them around every minute or so for three or four minutes.
In the meantime, I spread a pat of butter on one side of each slice of bread. For the cheese, I used once slice of provolone, put the onions on that, then put a slice of aged white cheddar, then on the skillet for one minute per side with a small cutting board on top as a press. After the time on the skillet, the sandwich was put it in the toaster oven at 350 for 2 minutes to ensure thorough meltiness and a crispy exterior.
Not one of my healthy choice options, but really really yummy!