Preheat the oven to 375 degrees
In a large bowl whisk together the sugar, tapioca, cinnamon, and nutmeg.
Using a large spoon gently stir in peaches and lemon juice
Spray an 11x7 baking pan with cooking spray. If you do not have the exact size dish that's ok, just try to keep it close to this size. Just be sure your casserole dish is at least 2 1/2 inches deep.
Add peach mixture to your baking pan. Be sure to use a rubber spatula to scrape all the sugar and tapioca out of the bowl.
Slice the butter into 4 or 5 slices. Place on top of the peach mixture, distributing evenly.
Remove your boxed pie dough from the refrigerator. Carefully roll out one round sheet of the dough onto your counter.
With a 12 inch ruler, make even marks the ruler's width by pressing the ruler down on the pie crust. Do this all the way across the dough. Using a long sharp knife, cut the dough into strips where it was marked with the ruler's edge.
Lay pie crust strips across one length of the baking dish.
Pull back every other strip. Add pie strips going in the opposite direction. Repeat until you have woven the pie crust strips into a basket pattern.
Trim excess pie dough strips from around the edges of the baking dish.
Crack the egg into a bowl and beat it thoroughly with a fork. Add 2 tablespoons of water and a pinch of salt. Stir until combined.
Apply egg wash using a pastry brush over the woven pie dough. Sprinkle with a pinch of sugar.
Bake in 375 degrees preheated oven for 50 minutes or until peaches are soft and the crust is golden brown.
Remove from oven and allow to cool 15 minutes or so before serving. Serve with a scoop of vanilla ice cream or whipped topping.