Bring a small pot of water to a boil. Add sweet potato and boil until very tender (about 7-10 minutes).
In a mixing bowl, mash sweet potato thoroughly, then add protein powder, sweetener and pie spice and mash again. If you like a totally smooth consistency, consider using an immersion blender.
Add sweet potato mixture to a mini casserole dish or to several ramekins.
In a small pan, melt butter. Add pecans and salt and toss until pecans are thoroughly coated.
Top mini casserole or ramekins with nut mixture and bake at 350 for 15 minutes or until nuts are toasted.