Preheat the oven to 350 degrees. Coat a 9×13 baking pan with olive oil spray.
Place the cooked sweet potato flesh, eggs, coconut oil, honey, vanilla extract and peppermint essential oil in the base of a food processor.
Process until smooth, scraping down the sides as needed.
In a mixing bowl, combine the spelt flour, cacao powder, salt, and baking powder.
Add to the food processor and process just until combined, scraping down the sides as needed.
Scrape the batter into the prepared pan and bake in the preheated oven for 15-17 minutes, or until a toothpick inserted in the center comes out clean. Be careful to not over-bake these, they are best removed when just set.
Remove the brownies and let cool completely.
In a microwave safe bowl, add the chocolate chips and 1/4 cup of the coconut milk.
Microwave for 45 seconds.
Whisk the melted chocolate and coconut milk together until smooth.
Add in the remaining 1/4 cup coconut milk and whisk until smooth. Let set at room temperature for 30-45 minutes, or until cooled and thickened. Add peppermint essential oil. Add one drop at a time and taste test until desired level of peppermint is reached.
Frost the brownies with the ganache and cut into squares. Store covered at room temperature or in the refrigerator.