A Different Grilled Cheese

I saw a cool way to make a healthier version of the grilled cheese sandwich on television, so I attempted my own.  I caramelized some onions, then threw in fresh spinach until it was cooked down.  Then I placed the mixture on toasted bread, topped with cheese I had in the fridge (Gouda - but I think pepper jack would be good too!) and broiled it in the oven - open-faced.

It was great!