Slice mushrooms. Saute in butter, add chives and seasoning. Mix the eggs lightly with a fork and add ½ teaspoon salt. Do not beat eggs stiffly thinking the omelet will be lighter. On the contrary, it will become heavier and watery. Add milk to eggs Heat a generous amount of butter in a heavy iron skillet and pour in the eggs. Bake in 400° oven for 20 minutes. Cut omelet in half, spread with mushrooms and cover with the other half. Serve immediately.