Elizabeth saw this recipe from the Barefoot Contessa and changed up the ingredients a bit.
Here's the link to the original...
We bought some prosciutto and a German cheese called Hirtenkase to replace the ham & Gruyere. The Hirtenkase is a super-strong cheese, like an Emmentaler or strong Swiss cheese with the crunch of a Parmesan. Elizabeth left out the mustard because the cheese was so strong and had that bit of zestyness that Dijon would've brought.
This came out of the oven golden brown and delicious...we sliced it up into pieces to have with some wine, but saved some an reheated it for breakfast.