1Heat oven to 350 degrees.Wash mushrooms and pat dry with towel.Take off stems, place caps on a sheet pan
put stems in a food processor, pulse until roughly chopped.
2Brown and finely crumble sausage.Set aside on paper towel lined plate.Add onions and garlic to the same skillet,cook for two minutes over medium heat add white wine to deglaze pan and allow liquid to evaporate.
3Add chopped mushroom stems cook for 2 minutes and salt and pepper to taste.Set mixture aside in a large bowl to cool. Add cream cheese,egg yolk and Parmesan cheese to sausage and mushroom mixture and mix well.Cool in refrigerator for 35 minutes.
4Spoon a generous amount of mixture into each mushroom cap.Bake at 350 degrees for 20-25 minutes or until golden brown.Be sure to allow to cool before serving.