Preheat oven to 325 degrees.
Grease or line a 8x8 inch baking pan with parchment paper.
Steam or microwave the sweet potato until soft enough to mash. Let cool, remove the skin, and mash to a puree consistency.
Microwave the peanut butter on the melt or soften setting for about 30 seconds. This will make the peanut butter easier to combine with the other ingredients.
In a large bowl combine the sweet potato puree, peanut butter, mashed banana, applesauce, and vanilla extract. Stir until thoroughly combined.
In a separate bowl combine the flour, sugar, cocoa powder, baking soda, and salt.
Add the dry ingredients mixture to the wet ingredients mixture. Stir until thoroughly combined.
Fold about ¾ cup of the chocolate chips into the batter.
Pour batter into prepared pan and top with the remaining chocolate chips.
Bake for about 25 minutes for gooey brownies, about 30 minutes for firmer brownies.