Mushroom Gratin - cooking recipe

Ingredients

4 tablespoons butter
2 small onions, finely chopped
2 lbs white button mushrooms, chopped
1 1/2 tablespoons dry vermouth
2/3 cup sour cream
3/4 cup white sauce
1/3 cup snipped fresh chives
1 pinch freshly grated nutmeg
1/2 teaspoon fennel seed
salt & freshly ground black pepper
3/4 cup grated gruyere cheese

Preparation

Melt the butter in a skillet and saute the onions until they begin to color, about 8 minutes. Add the mushrooms and saute until they release their liquid, then until it is evaporated and mushrooms are nicely browned, about 18 minutes. Stir in the vermouth and cook for 3 minutes.
Preheat the oven to 425 degrees.
Stir the sour cream, 1/2 cup of the white sauce, the chives, nutmeg, fennel seeds and salt and pepper. Mix well. Cook for 3 minutes.
Divide the mixture among 4 ovenproof ramekins or custard cups. Spread a tablespoon of the remaining white sauce over each portion and sprinkle generously with Gruyere. Bake for 15 minutes or until bubbly and browned.