Peel, core and slice pears thinly into a large mixing bowl.
Add granulated sugar, cinnamon, nutmeg and flour.
Stir until very well combined.
Allow the mixture to sit out about 30 minutes so the sugar forms a syrup.
Meanwhile, preheat oven to 300º.
Roll out pie crust for the bottom and top of pie.
Fit bottom layer into a 9 or 10-inch deep dish pie plate.
Place butter into the crust.
Top with pears, then fit top crust overtop of the pears and flute edges.
Place pie on a cookie sheet pan to catch drips while baking.
Place pie in preheated oven and bake until the syrup starts bubbling up and thickening at the top.
This will take one and a half to two hours.