Preheat oven to 190 degrees C.
Grease 8×8 pan with coconut oil and line it with parchment paper.
In a bowl, combine avocado, sweet potato, applesauce, honey or maple syrup and vanilla. Once creamy, add in cacao powder.
Add in eggs one at a time.
In a separate bowl, combine coconut flour, arrowroot flour, salt and baking soda.
Combine both mixtures until smooth.
Transfer to greased pan and bake for 25–35 minutes.
While baking, combine the last 5 ingredients listed in a separate bowl and mix until creamy and smooth.
Once the brownies are done baking and have cooled, frost with this mixture.