To a medium bowl, mix together the sliced pears, apples, brown sugar, creme fraiche or sour cream, flour, ginger, lemon juice and salt. Set aside.
Lightly flour your work surface and rolling pin. Roll out the first pie crust, rotating and flouring it every so often so it doesn’t stick to the surface, to a 13-inch circle. Roll the dough over the rolling pin and place it over a 9-inch pie dish. Transfer to the fridge while you roll out the second pie crust.
Roll out the second disk of dough and create a topping however you like. Do a normal lattice, an intricate lattice, make braids. The possibilities are endless, just remember that the freezer is your friend. If your pie dough ever becomes too soft to manage, be sure to put it on a cutting board and stick it in the freezer for 5 to 10 minutes. It’ll instantly become easier to work with.
Remove the pie dish from the fridge and pour in the filling, including all the juices that the pears and apples have released—this is the good stuff! Place the pie crust on the top however you like and seal it up! Transfer the whole pie to the freezer for about 20 minutes (this will firm it up and eliminate the possibility of shrinking like crazy).
Meanwhile, preheat the oven to 400 degrees F. Place the pie on a baking sheet and brush it with egg wash and sprinkle the top with turminado sugar. Transfer to the oven and bake for 30 minutes or until the pie is lightly golden brown. Turn the heat down to 350 degrees and bake for an additional 30 minutes.
Allow the pie to cool for at least 30 minutes, if you’re impatient. If you want sliceable slices that stay in tact, allow the pie to cool for 2 to 3 hours.