Mushrooms Polonaise - cooking recipe

Ingredients

1 1/2 lbs fresh mushrooms, thickly sliced
1 tablespoon olive oil or 1 tablespoon vegetable oil
1 onion, chopped
3/4 cup butter, plus
2 tablespoons butter, divided
2 tablespoons flour
1 cup sour cream
1 cup heavy whipping cream (unwhipped)
1/2 teaspoon nutmeg
salt and pepper
1/2 cup chopped fresh parsley
1/2 cup breadcrumbs (or more if desired, just add more butter)

Preparation

Set oven to 350 degrees.
Place the mushrooms in a skillet, with olive oil.
Cook slowly until wilted, but not browned.
Add in 1/2 cup butter.
When the butter has melted, add in the flour; cook, stirring constantly for about 5 minutes, over very low heat.
Stir in sour cream and the whipping cream with a wooden spoon, then add the nutmeg, salt and pepper(to taste).
Continue to cook, uncovered until mixture has thickened.
Stir in parsley.
In another small saute pan, lightly saute the bread crumbs in 1/4 cup plus 2 Tbsp butter.
Transfer the mushroom/cream mixture into a buttered shallow baking casserole dish.
Sprinkle the top with sauteed bread crumb/butter mixture.
Bake until mixture has set, and the bread crumbs have browned a little more.