1) To make the pastry: In a medium bowl, whisk together the flours and salt. Work in the butter until the mixture forms coarse crumbs.
2) Drizzle water onto the mixture while fluffing it with a fork. When you can squeeze the dough gently and it holds together, scoop it out onto a piece of parchment or waxed paper and fold it over on itself three or four times to build flaky layers.
3) Pat the dough into a rectangle, wrap it in plastic wrap or waxed paper, and chill for 30 minutes.
4) To make the filling: Stir together all the filling ingredients.
5) Preheat the oven to 425°F. Unwrap the dough and roll it into a long rectangle, 9" wide x 17" long. Use a sharp knife or pizza wheel to trim 1/2" off the outside edges, leaving a rectangle 8" x 16". Trimming the edges will give you a neater look and a higher-rising pastry.
6) Cut the dough into eight 4" squares. Place 2 tablespoons of the apple filling on each square. Use a pastry brush to lightly wet two adjoining edges of each square, and fold the dough over the filling to make a triangle. Press the edges to seal (or use a fork), and transfer the pastry to a parchment-lined baking sheet. Repeat until all the squares are used.
7) Bake the turnovers for 25 to 30 minutes, until they're golden brown. Remove them from the oven and cool them on a rack before serving or drizzling with a simple confectioners' sugar and milk glaze.
Yield: 8 turnovers.