Preheat the oven the 350 degrees F. Line a muffin tin with cupcake liners.
In a large bowl or stand mixer, combine the cacao powder, coconut sugar, coconut flour, tapioca starch, baking powder, and sea salt. Stir to blend.
In a separate medium bowl, whisk together the mashed sweet potato, eggs, coconut oil, maple syrup, and vanilla extract.
Pour the wet ingredients into the bowl with the dry ingredients and beat until a batter is formed (it will be thicker than a traditional cupcake batter).
Spoon the batter into each cupcake liner, filling each one to the top. Bake 22 to 25 minutes. Allow the cupcakes to completely cool to room temperature (at least an hour) before frosting.
To make the frosting, combine the grass-fed butter, coconut oil, and peanut butter in a large bowl. Using a hand beater or hand blender with the whisk tool, beat until fluffy, about 30 seconds. You can also use a large whisk to beat by hand.
Add the powdered monk fruit and beat again until all of the ingredients are combined. Use a spatula to scrape down the sides as needed. Give the frosting a good stir with the spatula. You can frost the cupcakes once cooled, or place the frosting in the refrigerator for 10 minutes for a firmer texture.