Saute onions, garlic and mushrooms in a 1 Tblsp butter until soft. Chop with a knife or place in food processor and blend coarsely.
4
Make a thick white sauce.
5
Melt the butter in a saucepan and add the flour, stirring with a wooden spoon. Gradually add the milk, stirring rapidly with whisk. When blended and smooth, add the salt, pepper, cayenne. Simmer gently for 5 minutes stirring the bottom regularly to ensure it doesn't burn.
6
Remove sauce from heat and whisk in egg yolks, herbs, mushrooms and cheese. Sauce should be thick and creamy.
7
Whip the egg whites until stiff and gently fold into the mixture, a little at a time.
8
Spoon into buttered souffle dishes and bake in a hot oven 200C/400F for 20-25 minutes until well risen. Do not open the oven door during cooking.