Thaw phyllo dough in the refrigerator overnight or according to package instructions. Keep refrigerator until ready to use.
Melt 1 tablespoon of butter in a medium saucepan over medium heat. Add the apples and stir to coat. Add the vanilla extract, lemon juice, brown sugar, cinnamon, nutmeg, ginger*, and salt. Stir occasionally and cook 6-7 minutes, until apples begin to soften.
In a small bowl, whisk to combine the cornstarch and cold water. Pour mixture into the apples. Stir and cook for another 2-3 minutes until apple mixture thickens. Remove from heat. Allow to cool to room temperature before using.
Melt the remaining butter in a small bowl. Take out a pastry brush, sharp knife, and clean damp kitchen towel. Line a baking tray with parchment paper and preheat oven to 375 Fahrenheit.
Place one sheet of phyllo dough horizontally on a large cutting board, the kitchen counter or a sheet of parchment paper. Brush the sheet of phyllo dough evenly with melted butter. Cover the remaining layers with a clean, damp (but not too damp) kitchen towel.
Lay another sheet of phyllo dough on top. Brush with butter. Repeat with one more sheet of phyllo dough. Cut phyllo dough in half then cut each half in half. You should have four equal strips.
Place about two tablespoons in the bottom of one strip. Leave a little room at the edges. Fold the bottom left corner over the filling to meet the right edge to make a triangle shape. Continue folding and keeping a triangle shape as you fold. Continue as if you are folding a flag. Then place the triangle seem side down on a baking sheet. Repeat the process til you have 8 turnovers. Brush the tops with a little extra butter.
Bake at 375 Fahrenheit for 18-21 minutes. Bake until pastries are crispy and golden brown. Allow to cool slightly before eating. Sprinkle with powdered sugar, if desired.