I have made french onion soup twice in the past few weeks, and both times the cheese on top has basically fallen apart into pieces under the broiler and refused to brown even a bit. The result is almost curdled . . . not stringy or chewy as it should be. It's like the cheese disintegrates into the soup itself.
I am at a total loss, seeing as how I have made this soup in the past with good results. I can't figure out what happened. I am using the same crocks I have always used. I am using imported gruyere, and shredding it right beforehand. I am using french bread that I toast to ensure it's dry (I used a french baguette both times). I am filling the crocks about 3/4 full, then putting several croutons on top to cover the top (and mound up a bit), then mounding cheese on top of that.
Any ideas? Are my croutons too thin at about 1/2 inch? Is it the quality of the cheese? I think it's happening because the liquid is coming up and saturating the cheese, but I don't know how to prevent this!