Preheat oven to 400 degrees F. Place coconut milk can, a mixing bowl, and whisk attachment in the freezer.
Poke holes in sweet potatoes and bake for about 1 hour until soft. Remove skin and mash in a large bowl.
Slowly mix in oat flour, baking powder, and baking soda until combined. Cover bowl with a dish towel and let rise for 30 to 60 minutes.
Once dough has risen, flour a large surface and roll out to about 1/8 inch thickness.
Sprinkle dough evenly with cinnamon and coconut sugar. Roll up lengthwise and cut into 6 pieces.
Grease a baking dish or cast-iron skillet with avocado oil spray. Place buns in the dish and bake for 15 to 20 minutes.
While buns are baking, remove chilled materials from the freezer. Using a mixer on high, beat coconut milk, monk fruit sweetener, and vanilla until stiff peaks form.
Top cooled cinnamon buns with coconut icing and chopped walnuts before serving.