Preheat oven to 375 degrees F.

Crimp and freeze crust for at least 1 hour before baking. If using premade store-bought crust, freeze until ready to use.

While crust is freezing, wrap purple sweet potato in foil and bake at 375 degrees for 1 hour, until soft. To test for doneness, pierce sweet potato with a fork. If it pierces easily and feels soft, it’s done. If still firm, bake for an additional 10 minutes. Remove from oven and cool.

Once sweet potato is cool enough to handle, unwrap foil and remove the skin. Place sweet potato in mixer and mash with paddle attachment until fully mashed. This can also be done with a hand beater.

Add melted butter to sweet potato and mix thoroughly. Add sugar, cardamom, ginger, salt, and orange zest to sweet potato mixture and mix until combined. Introduce eggs 1 at a time until mixed, then add milk. Mix until just combined and silky.

Remove crust from freezer and pour filling into baked crust until filled ¾ of the way.

Bake at 375 degrees for approximately 40 minutes, until pie filling is firm. Internal temperature should be 190 degrees. Allow pie to cool and decorate with granola and thyme.