Preheat oven to 375 degrees Fahrenheit.

Melt butter in medium saucepan and whisk in flour to make a roux. Add milk and whisk until smooth and thick over low medium heat. Whisk insult, nutmeg, cayenne, black pepper.

Beat half of the bechamel mixture into the egg yolks and the Swiss cheese.

Combined with the rest of the bechamel sauce and beat vigorously to blend.

Add spinach to the mixture.

Beat egg whites with a pinch of salt until stiff peaks form.

Stir one quarter of egg whites into souffle to lighten, and fold in the rest of the egg whites.

Bake in buttered pan until risen and golden, for 20-25 minutes. Serve immediately on small plates or as filling in crepes.