Preheat the oven to 350°F (180°C). Line a 6-inch (or 8-inch) brownie pan with parchment paper and grease it with cooking oil. Set aside. In a large mixing bowl, stir applesauce, peanut butter, and cocoa powder using a silicone spatula until the batter is moist, thick, and consistent. Taste the batter; if it is too bitter, stir in the semi-sweet chocolate chips (I used 55% cocoa vegan chocolate chips). Pour the batter into the prepared brownie pan and spread evenly. If you like, sprinkle some extra chocolate chips on top.
Bake the brownies on the center rack of the oven for 25-35 minutes at 350°F (180°C), or until a toothpick inserted in the center comes out with only a little sticky crumb on it. If they are too wet, keep baking. If desired, you can foil the pan. Let the brownies cool down in the pan for 10 minutes, then transfer them to a cooling rack and cool completely before slicing. An hour is the best as less than that leaves the brownies fragile when cut. If it is too fragile, pop the brownies in the fridge to firm them up.