1 large baking apple (such as Granny Smith), peeled, cored, cut into 1/4-inch dice
3 Tbsp dried currants
2 Tbsp chopped walnuts
1/4 cup sugar
1/4 teaspoon cinnamon
1/2 teaspoon corn starch
1/4 cup apple sauce
1/8 teaspoon vanilla
1 frozen puff pastry sheet, thawed OR 2 pâte brisée dough recipes (enough for a double crust pie)
2 Tbsp butter, cut into bits
1 large egg, lightly beaten
1 teaspoon milk
1 Put oven rack in lower third of oven and pre-heat oven to 400°F. Butter a large baking sheet (or use Silpat).
2 In a medium bowl, mix together apples, currants, and walnuts with the sugar, cinnamon, and corn starch, making sure the fruit and nuts are well coated. Mix in the apple sauce and vanilla.
3a Unfold the thawed pastry sheet on a lightly floured surface. Depending on the size of your pastry sheet you are going to want to cut the sheet into either four 5-inch-by-5-inch or six 4-inch-by-4-inch squares.
3b Roll out your pie dough on a lightly floured surface to a 16x11 inch rectangle. Trim the edges to 15x10 inches and cut into six 5x5-inch squares.
4 Divide the apple mixture among the squares, leaving a 1-inch border. If you are using an already prepared puff pastry sheet, dot the mixture in each pastry with a little butter. (If you are using a butter pie dough, you can skip adding the extra butter.) In a small bowl mix the beaten egg with a teaspoon of milk. Use a pastry brush to brush the egg mixture on the border of the pastry.
5 Fold each pastry into a triangle, enclosing the filling, and crimp edges with a fork. Brush the tops of the pastries with more of the egg wash. Cut 2 or 3 small steam vents in the top of each turnover.
6 Place the pastries in the oven and bake at 400°F for 20 minutes, or until puffed and golden.
Cool turnovers to warm before serving.