Preheat your oven to 230 C (450 F). Place a baking sheet on the bottom rack.
Add the pear slices to a large mixing bowl. Mix together the sugar, flour, nutmeg, and lemon zest and sprinkle over the pears and toss to mix in.
Roll out the first crusts and line a 9 inch pie dish, pour in the pear mixture.
Roll out the second pie crust and place on top of the pie, flute the edge to your preference. Cut a few slits in the top crust.
Beat the egg with a tablespoon of water, brush this on the top then sprinkle some sugar on the top (makes a nice and golden crust to give a sweet crunch).
Place pie on the baking sheet and bake sheet for 10 minutes, then reduce the temp to 180 C (350 F) and bake for another 35 to 40 minutes, or until the crust is golden brown.
Cool for several hours before serving. Serve with whipped topping or ice cream as desired.