In a mixing bowl, combine the Greek yogurt, egg, cocoa powder, flour, and maple syrup. Mix until well combined and smooth. Add the chocolate chips.
Once the waffle iron is heated, lightly grease it with non-stick cooking spray or melted butter.
Pour the batter onto the preheated waffle iron, spreading it out evenly to cover the surface.
Close the waffle iron and cook the waffles according to the manufacturer's instructions, until they are slightly crispy on the outside.
Once cooked, carefully remove the waffles from the iron and transfer them to a plate. Serve with maple syrup or peanut butter.