For the pastry:
2-1/2 cups unbleached all-purpose flour
1 tablespoon sugar
1/2 teaspoon salt
8 ounces (2 sticks) cold, unsalted butter, cut into cubes
1/3 cup cold water
For the filling:
12 ounces fresh or frozen cranberries
1-1/4 pounds of apples, peeled, cored and thickly sliced (any good pie apple will do)
1 cup pure maple syrup
1 tablespoon freshly grated orange rind
4 teaspoons cornstarch, dissolved in 1-1/2 tablespoons cold water
1/2 cup roasted walnut halves
For the egg wash:
1 egg, beaten with 1 tablespoon cold water
Prepare the pastry. Combine flour, sugar and salt in a bowl or food processor. Mix briefly. Cut in butter until pieces form the size of peas. Add water and mix just to moisten. Form a ball of dough, divide it in half and wrap each disk in plastic wrap. Refrigerate for at least 1 hour.
Prepare the filling. Combine cranberries, apples, maple syrup and orange rind in a large saucepan. Bring the mixture to boil over medium heat. Cook and stir until cranberries have popped and apples are beginning to soften. Stir in cornstarch slurry and simmer until thickened, about 1 minute. Remove from heat and stir in walnuts. Allow filling to cool to room temperature.
Assemble and bake the pie. Heat oven to 375 degrees. Roll out one disk of dough on a lightly floured surface and line a 9-inch pie plate with pastry. Roll our remaining dough and cut strips for a lattice top. Fill pastry-lined plate with filling. Cover with woven strips to form lattice top. Brush pastry with egg wash. Bake pie on a sheet pan in the middle of the oven for 1 hour, or until pastry is golden brown and filling bubbles through the lattice top.
Cool to warm or room temperature before serving. Delicious with whipped cream, a scoop of vanilla ice cream or full-fat Greek yogurt.