Peel potatoes, and cut into large wedges (i did 3 wedges per potato), place potatoes in large microwave safe bowl covered with saran wrap, pierced a few times to let out steam. Put bowl in the microwave for 5-6 minutes, or until potatoes are fork tender. Remove saran wrap and let cool (do this carefully so you don't burn yourself on the steam!)
Note: You could also boil the potatoes in a pot of boiling water for about 10 minutes or until they are fork tender.
Meanwhile, place the rest of the ingredients in a blender or food processor, and mix until everything is well combined. When the potatoes are cooled, place the potatoes in the blender with the rest of the ingredients and mix until smooth. (Or you could pulse it and leave some of the potatoes a bit chunky if you prefer your casserole to have more texture rather than a smooth filling.)
Spray your crockpot with cooking spray. Pour sweet potato mixture into crockpot. Meanwhile,to make the topping, combine the topping ingredients in a small bowl and mix to combine. Sprinkle topping over sweet potatoes and cook on high 3-4 hours or on low 6-8 hours.