Leek and Potato Soufflé with Ham and Fontina

Recipe from: David Tanis for the New York Times

1 1/2 lbs. potatoes, peeled and chopped

1 1/2 cups half and half or milk

salt and pepper

2 Tablespoons butter

2 medium leeks, white and tender green parts, diced (about 2 cups)

1 teaspoon chopped fresh thyme

2 garlic cloves, minced

pinch of cayenne

grated nutmeg, to taste

4 ounces thick cut cooked ham, diced (optional)

4 ounces grated gruyere or fontina

3 eggs, separated

1 tablespoon butter for buttering your baking dish

1 ounce finely grated parmesan

Heat your oven to 375º.  In well salted water, boil the potatoes until tender, drain, and put in a large mixing bowl and mash with the half and half or milk.  

Heat 2 tablespoons butter in a skillet over medium heat.  Add the leeks and season with salt and pepper.  Cook until softened but still bright green (3 - 4 minutes).  Add the thyme and garlic and cook for 1 minute more.  Add the leeks to the mashed potatoes and mix well.  Add the cayenne, nutmeg, ham (if using) and gruyere or fontina.  Mix well, taste and adjust the seasoning.  Beat in the the 3 egg yolks.  

Butter your baking dish and sprinkle the bottom and sides with half of the grated parmesan.  

In a clean bowl, beat the egg whites to stiff peeks.  Stir 1/3 of the beaten whites into the potato mixture to lighten it and then fold in the rest.  Scrape the soufflé into the baking dish.  Sprinkle with the remaining parmesan.  Bake for 40 minutes, until nicely browned.  Check the center for doneness with a skewer and let rest for 10 minutes or so before serving.