Preheat the oven to 375.
Wash and dry the sweet potatoes.
Pierce each sweet potatoes with a fork.
Cook for 60-70 minutes until tender.
Take a slice off the top of each potato toget access to inside.
Scoop out the insides leaving about 1/4" around the outside of the sweet potato. Place scooped out potato in medium bowl.
To the bowl with scooped potato, add 1/2 cup brown sugar, vanilla, milk and 4 tablespoons butter.
Beat with hand mixer until fluffy.
Put the whipped potatoes back into the potato shells.
Place mini marshmallows on top or each.
In a small bowl, melt 2 tablespoons butter in microwave.
Add flour, 1/4 cup brown sugar, quick oats, cinnamon and nutmeg.
Mix together with a fork until crumbly.
Sprinkle mixture over marshmallows.
Bake for 15-18 minutes until top is browned.