First, line your muffin tin(s) with cupcake liners, and set them aside.
Wash the sweet potato, and place it in the microwave on the baked potato setting and cook the sweet potato. When it's done, set it aside to cool.
In the mixing bowl of a stand mixer, cream together the softened butter, and brown sugar.
Slice the sweet potato in half, and with a large spoon, scoop out the sweet potato and place it in the mixing bowl, and blend with the other ingredients.
Add the cake mix, eggs, milk, and Maple syrup, and blend on low until all ingredients are well blended.
Then, blend on high for about 45 seconds.
Scrape down the sides of the mixing bowl, and blend one more time.
Remove the mixing bowl, and with a small ladle, ladle the cake mixture into the cupcake liners until they're about 2/3 full.
Bake in a 350 degree oven for 18 - 22 minutes, or until a toothpick comes out clean. Remove from oven, and cool on wire racks.
While the cupcakes are cooling; make the frosting.
Place the stick of softened butter in the mixing bowl, along with the Crisco, and Vanilla, and blend together until smooth and creamy.
Add the cinnamon, and blend well to mix.
Add about half of the powdered sugar, and half of the heavy cream, and mix on low until blended. Add a little more of powdered sugar, and more of the cream until all ingredients have been added.
Stop the mixer and scrape the sides, and blend again on high until the frosting is thick and smooth. Place the mixing bowl in the refrigerator to chill.
While the frosting is chilling, and the cupcakes are cooling, make the Topping: Line a cookie sheet with Parchment paper.
Place the Oatmeal, brown sugar, cinnamon and sugar in a large bowl, and pour the melted butter over the topping mixture, and blend well with a large spoon.
Pour the Topping onto the Parchment paper lined cookie sheet, and place in the oven at 400 degrees for about 10 minutes, stirring halfway through baking, bake until golden brown.
Remove from oven and set aside to cool.
Line another cookie sheet with Parchment paper, and place 24 Marshmallows on the parchment paper. Place the cookie sheet in the oven, under the broiler, watching constantly until the marshmallows begin to brown and melt.
Remove from oven, and set aside.
When the cupcakes are completely cooled, fill a pastry bag with the Cinnamon buttercream frosting, and using the large star tip, pipe the frosting onto the cupcakes, starting at the outer edge, and swirling up to a point.
Gently roll the cupcake edges, where the frosting is, in the TOPPING, and place a browned, melted Marshmallow on top of the frosting. Serve and Enjoy!