Preheat oven to 375° F. Spray a nonstick muffin pan with cooking spray or line with paper liners.
In a medium mixing bowl whisk together white whole wheat flour, all-purpose flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
¾ cup (90g) white whole-wheat flour, ¾ cup (90g) all-purpose flour, ½ cup (40g) unsweetened cocoa powder, 1 ½ teaspoons baking powder, ½ teaspoon baking soda, ½ teaspoon salt
In a large mixing bowl whisk together the melted butter, honey, mashed banana, Greek yogurt, eggs and vanilla.
⅓ cup (75g) unsalted butter, ⅓ cup (112g) honey, 1 cup (225g) mashed very ripe banana, ½ cup (115g) plain Greek yogurt, 2 large eggs, 1 teaspoon vanilla
Pour the dry ingredients into the wet and mix with a rubber spatula until almost combined. Gently mix in the chocolate chips until everything is just combined. Do not over-mix. The batter will be thick.
½ cup (100g) chocolate chips
Scoop the batter into the prepared muffin pan, dividing it evenly between the 12 muffin cups. Bake for 15 to 18 minutes, until a tester inserted into the center of a muffin comes out clean (except for maybe melted chocolate chips). Let muffins cool in the pan for 10 minutes and then remove to a wire rack to finish cooling.