Mushrooms Polonaise - serves 6

1 1/2 lb mushrooms, sliced
1 onion, chopped
3/4 cup butter
2 tbsp flour
1 cup sour cream
1 cup heavy cream
1/2 tsp nutmeg
Pepper
1/2 cup parsley, chopped
1/4 cup bread crumbs

Preheat oven to 350F. Place mushrooms and onion in a heavy nonstick skillet with a tiny bit of olive oil. Cook slowly until wilted but not browned. Add 1/2 cup of butter.
When butter has melted, add flour and cook, stirring constantly, for 5 minutes over very low heat. Stir in sour cream and heavy cream with a wooden spoon, then add nutmeg and pepper to taste. Continue to cook, uncovered until mixture has thickened. Stir in parsley.
In another pan, lightly saute bread crumbs in 1/4 cup of butter. Pour mushroom mixture into a buttered shallow casserole. Sprinkle top with sauteed bread crumbs. Bake until mixture has set and bread crumbs have browned a little more.