To bake the pie, pack the cooled filling into a 9 inch pie pan, leaving 1/2 on the top (resist the urge to pack the pie pan full, if you have extra filling.
Mix the riced potatoes with the egg, cream and butter, then spread on the cooled filling.
Use a fork to make lines in the potato crust, which will add dimension and get crisp. Alternately, use a pastry bag with a fluted tip for a fancy presentation. If you can manage, spray the top of the crust with oil (I use a spray bottle--this is optional but makes for a crustier crust.
Preheat the oven to 375F. Put the pie on a baking sheet just in case some of it migrates out while cooking, then bake for 30-45 minutes, increasing the heat to 425-450F at the end to help it brown if needed. Allow to rest for a few minutes before serving and warm guests that it will be hot.