Place cleaned sweet potatoes on an aluminum lined baking sheet and cook for 1 hour to 1.5 hours or until softened.
Allow sweet potatoes to cool to room temperature.
Set oven to 350 degrees.
Prepare pie crust and set to the side. If using rolled pie crust spray pie pan, then place crust in pan. Pierce a few holes in crust with fork.
Peel skin from sweet potatoes and place in blender. Remove any long, stringy fibers.
Add additional ingredients to blender. Beat mixture until smooth and pour into prepared pie crust (s).
Bake for 40-45 minutes, or until toothpick comes out clean. Allow pie(s) to cool on cooling rack.
This recipe with yield enough mixture for 2 regular-size pie crusts. If using a deep-dish pie pan depending on size may only yield enough mixture for 1 pie. You can substitute regular milk or buttermilk if kefir is not available.