Melt the margarine and add the flour. You can use a saucepan for this.

Gradually pour in the milk, then transfer the mixture to a saucepan over low heat.

Cut the ham into small pieces and add to the saucepan. Then add the Swiss cheese.

Beat the egg whites until stiff peaks form, then gently fold them into the mixture in the saucepan. Stir gently to keep the egg whites fluffy.

Butter and flour the baking dish, then pour in the mixture.

Bake for 15 minutes at 250°F (120°C), then for 10 minutes at 350°F (180°C).