Soupe au chou gratinée

Here's a variation on the classic French onion soup. We had (and still have) a good deal of broth from the potée (boiled dinner) that Ken made last weekend, so we decided to make a cabbage soup by chopping up the tender cooked cabbage and adding it back into the broth, then preparing it like French onion soup.

Two bowls of steaming cabbage soup.

First, Ken took the cabbage leaves out of the broth and strained the other vegetables out. He chopped the cabbage and added it back into the strained broth, then ladled the steaming soup into individual bowls.

Add thick slices of baguette and grated cheese.

He made croutons by slicing a baguette and laying the slices on the surface of the soup. This is a great way to use day-old or slightly stale bread because it soaks up the broth and softens. If the bread is fresh, you may want to lightly toast it so it doesn't disintegrate in the broth.

Melt the cheese in the oven and serve with freshly ground black pepper.

Finally, he sprinkled grated cheese on top of the bread slices. In this case, the cheese was a French (as opposed to Swiss) gruyère. Then the bowls went into the oven until the cheese melted. Et voilà !

For all you French experts out there, do you write soupe au chou in the singular as I did or in the plural (soupe aux choux)? I've seen it both ways on the internet. I chose the singular if for no other reason that only one chou went into the potée, but I don't know if that's how most people would do it.