For the dough, place cheese and butter in the mixer and beat until smooth and well blended.

Add flour and salt and mix until fully incorporated, scraping down the bowl.

Pat into a ball, wrap in plastic wrap, and refrigerate for one hour. Meanwhile, prepare filling.

Spray a large frying pan with cooking spray. Add butter and heat until melted.

Add onion and garlic and sauté until soft but not brown.

Slice mushrooms in a food processor with the slicer attachment. Add to frying pan and cook over low heat, stirring until tender, about five minutes.

Sprinkle mushrooms with seasonings and flour and stir together.

Add wine and mix.

Stir in sour cream. Heat just until thickened, then remove from heat. Taste and adjust seasoning if necessary.

Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).  Flour your work surface well.

Divide chilled dough in half and roll to a quarter to a half-inch(approximately one centimeter) thickness.

With a glass or a cookie cutter, cut into medium-sized rounds, about three inches (seven and a half centimeters).

Lightly brush each round with the egg wash mixture.

Place a small amount of filling on one side of each circle, then fold the dough over, pressing to seal. You can do this with a fork, if desired. Continue until all the dough is finished.

Brush tops with remaining egg wash and slide into hot oven. Bake for 15 minutes or until crispy and golden brown.

Serve with a sour cream/scallion dip if desired.