Mix together the sweet potato, tahini, and maple syrup.
In another bowl, whisk together the egg and vanilla. Then, whisk that in with the sweet potato mixture.
Mix the cacao powder, baking soda, and salt together.
Stir the dry mixture into the wet.
Pour the batter into an 8×8 baking dish that had been lined with parchment paper and sprayed with cooking spray.
Bake at 350 degrees for 20-25 minutes or until set in the middle.