Preheat oven to 350F. Line 12 cups of a muffin tin with paper liners.
In a small bowl, mix the chocolate chips and chopped walnuts together for the topping. Set aside.
In a food processor, puree the banana and dates until smooth.
Add all the remaining ingredients (except the topping) and pulse until a thick batter forms. Stop the machine a couple of times to scrape down the sides. Avoid overblending.
Spoon the batter into the muffin cups, filling each ⅔ full. Gently press 1 tablespoon of the walnut-chocolate chip topping mixture onto each of the muffin top. Quickly transfer to the oven, as the baking soda will have been activated and you don't want the muffins to deflate.
Bake for 16-18 minutes or until toothpick inserted in the middle comes out clean.
Remove from oven and cool in the pan for 15 minutes before cooling on a rack.