When I get a craving for caramalized onions, I make the time to cook a batch on the stove top. I know it's time consuming, but I'm always happy with the sweetness the slow cooking brings to these veggies. It's almost like making jam or jelly. And they're the perfect condiment (or star) for sandwiches, salads, pizza, soups, and savory bread puddings. This is one of my go-to sandwich recipes when I have caramalized onions and fontina cheese in the house.
In large pan on medium to medium high heat, add oil. When oil is glistening, add onions and stir to coat. Lower heat to medium or medium low (my stove cooks HOT, so I use medium low. Spread onions evenly in pan and let cook, stirring occasionally.
After about 8 minutes add salt and sugar. If onions seem to be drying out and sticking to the pan, add 2T water. Continue cooking onions about 30 minutes, stirring every so often. You'll know the onions are done when they're dark brown, dense and a bit gooey.
To make the sandwiches, mist stove top grill or griddle with cooking spray. Heat to medium/medium low. Place onions on one side of four slices of bread. Top onions with hand-shaven fontina cheese (the more the better), cover with reserved slices of bread and place on grill.
Cook about 3-4 minutes on each side. You can also place a heavy saucepan on top of the sandwiches to get that pannini press look, but I'm a fan of the natural grill marks.
When the cheese is oozy and hot, your sandwiches are done. Slice, enjoy, and get ready to make some more, they're that good!