Step 1

Preheat the oven to 350 degrees F (175 degrees C). Grease a 2 quart casserole dish, and coat the inside with Parmesan cheese.

Step 2

Melt the butter in a saucepan over medium heat. Whisk in flour, and gradually whisk in milk so that no lumps form. Cook, stirring until thick and light brown in color. Remove from heat, and stir in the mustard and cayenne pepper. Whisk in the egg yolks, and Cheddar cheese, then stir in the ham. Set the mixture aside.

Step 3

In a clean dry glass or metal bowl, whip the egg whites to soft but firm peaks. Fold the cheese mixture into the egg whites using a rubber spatula. Mix well, but not too long, or the mixture will deflate. It is okay to have some white streaks. Transfer the mixture to the prepared casserole dish.

Step 4

Place the dish in a larger shallow pan, and place them in the preheated oven. Fill the outer pan with water. The steam will help lift the souffle.

Step 5

Bake for 50 to 60 minutes in the preheated oven. Remove the casserole dish from the water bath. The souffle will have a golden color to the crust, and it may fall slightly when taken out of the oven. This is okay!