Line a large baking sheet with foil and set aside. Prepare double pastry crust. Roll out 1 disc of dough and fit into a 9-inch deep dish pie plate. Place the prepared pastry on the foil lined baking sheet. Set aside. Preheat oven to 425 degrees.
Peel and slice 6 cups of peaches and place in a large mixing bowl. Sprinkle with almond extract and lemon juice. In a small mixing bowl, whisk together the sugar, cornstarch, cinnamon and nutmeg. Pour over the peaches and toss gently to combine. Layer 1/2 the peaches in the prepared pastry. Spread 1/2 of the raspberries over the peaches. Add the remaining peaches and any juice, then top with the last of the raspberries. Set aside.
Roll out the remaining half of pastry into a circle larger than the top of the pie plate. Cut into equal width strips. Starting in the middle, lay one strip of dough across the middle of the pie. Select every other piece of dough and add to the top of the pie. Weave the remaining slices of dough in the opposite direction. Trim excess from strips. (See video for step by step directions.)
Dampen the edges of the crust with water and fold up the overhang. Press to seal. Crimp the edges in a decorative pattern.
Whisk together 1 large egg and 1 tablespoon milk. Lightly brush the egg mixture over the entire pie. Sprinkle with additional sugar if desired. Bake (on the foil lined pan) at 425 degrees for 15 minutes, reduce the heat to 400 and continue baking for about 45 more minutes. Check the pie after 30 minutes of baking and cover with foil if needed to prevent over browning.
Cool to room temperature or serve slightly warm.