Directions

1. Sift the flour and 1/2 tablespoon salt together into a large bowl. Blend in 8 ounces butter with your fingertips until most of the mixture resembles coarse meal with small (pea-sized) butter lumps. In a small bowl, beat one egg then remove half of it for egg wash, set aside. Then add vinegar with the other egg and add ice water and beat well.
   
2. Add the liquid to the flour mixture, stirring with a fork until incorporated. Turn the dough out onto a lightly floured surface and knead gently with the heel of your hand to bring the dough together.
   
3. Roll out into a 15-by-9-inch rectangle. Arrange the dough with the short side closest to you and fold into thirds like an envelope. Place in the refrigerator and chill for at least 1 hour, but no more than 6 hours.
   
4. Heat in a large skillet 4 tablespoons butter and olive oil over medium heat. Add the shallots and cook until golden, about 5 minutes. Stir in the mushrooms, dash of salt and pepper, and cook until soft, 6 to 8 minutes. Add the wine and broth and bring to a simmer. Cook, stirring often, until the liquid has almost evaporated, about 6-8 minutes. Stir in the crème fraîche and simmer until the liquid has almost all evaporated, about 10 minutes more.
   
5. Remove from the heat and transfer the mixture to a bowl. Place the bowl in the fridge. When the mixture is completely chilled, add the cheese.
   
6. Remove dough from fridge, roll out the dough with a rolling pin on a lightly floured surface. Roll out to approximately ⅛-inch thick and cut out 12 6-inch rounds. Preheat the oven to 375°F. Line a baking sheet with parchment paper.
   
7. Lay out the dough circles onto a lightly floured surface. Spoon 2 ounces of filling onto one half of each dough round. Press the filling down lightly to flatten, leaving a ½-inch border. Brush the egg wash around the border of the pastry. Fold the pastry half over the filling, stretching the dough to cover. Seal the edges with the tines of a fork and place on baking sheet.
   
8. Repeat with the remaining empanadas, leaving 2 inches between the empanadas on the pan. Press the edges of the empanadas again with a fork. Brush the tops of the empanadas with egg wash. Bake the empanadas for 10 to 15 minutes, or until golden brown.