Check out this paleo-friendly, gluten-free recipe from George Bryant, the man behind the blog "Civilized Caveman Cooking."
Preheat the oven to 350°F (175°C). Grease a 9-by-5-inch (23-by-12-cm) metal loaf pan and line it with parchment paper.
Combine the bananas, eggs, butter, and almond butter in a food processor or mixing bowl and mix well until the ingredients are well blended. Add the coconut flour, baking soda, baking powder, vanilla, and salt and mix together well.
In a double boiler over medium-low heat, mix together the swirl ingredients until the chocolate has melted.
Pour the bread batter into the prepared pan and spread it out evenly. As soon as you pour the batter, pour the chocolate swirl directly on top and use a knife to swirl the chocolate throughout the loaf pan.
Bake for 45 minutes or until a toothpick comes out clean when inserted in the middle. Remove from oven and let cool in the pan for 15 minutes before serving.