Boil water in a medium sized pot. While the water is boiling peal your sweet potatoes and dice into small pieces. Add to the boiling water and cook until fork tender.
To a stand mixer add your sugar and coconut oil and mix until creamed together.
Your potatoes should be ready by now, you want to drain and mash them with a potato masher. Take 1 cup of the mashed potato and add it to your sugar and oil mix.
Add your flax egg and mix until everything is combined. It should be a liquidy mix.
In a separate bowl combine your flour, baking soda and all your spices.
With your mixer set to low, slowly add in your flour mixture small amounts at a time until it is all mixed in. You should have a fairly elastic dough at the end.
Roll your dough into 15 even balls and place about 2 inches apart on a lined baking sheet.
Using something flat (like a measuring cup) press your dough balls down until they are disks.
Bake in the oven for 10-12 minutes or until golden around the edges.
Marshmallow Fluff
Add your marshmallow fluff ingredients in your stand mixer with the whisk attachment and whisk on low-medium for about 2 minutes, then on high for about 8 minutes or until stiff peaks form.
Be sure your cookies are completely cooled before you add your fluff or it will just fall off.
Because the icing is so light, it is okay to add quite a good layer of it to your cookies!
Notes
Pro Tip: Stiff peaks means you can form a peak with the mix and it doesn't fall over.