Preheat oven to 180°C fan (350°F). Line or lightly oil a small loaf tin (15x20cm 6 × 8 inches.)
In a bowl, combine mashed sweet potato, peanut butter, maple syrup, and yogurt.
Sift in cocoa powder and baking powder and mix until smooth.
Stir in most of the chocolate chips, reserving some for topping.
Transfer batter to the loaf tin, smooth the top, and sprinkle with reserved chips.
Bake for 30 minutes, turn off the oven and let it cool completely before slicing
