Place a rack in the centre of your oven and preheat oven to 350ºF.

Grease or line muffin pan with paper cups.

In a large bowl, whisk together the flour, sugar, baking soda and salt.

Sift the cocoa and whisk into the flour mixture.

In a separate bowl, whisk together the eggs, yogurt, oil, vanilla and mashed bananas.

Add the wet mixture to the dry ingredients and mix until blended.

Add in the chocolate chips, mix until just combined. To avoid tough muffins, do not over-mix the batter.

Evenly spoon the batter into the greased or paper-lined muffin cups.

Bake until a toothpick inserted in the centre of the muffins comes out clean, about 18 to 20 minutes.

Let the muffins cool in the pan on a rack for 5 minutes before removing them and placing onto a wire rack to cool.

Store the muffins in an airtight container up to 3 days. Muffins can also be stored in the refrigerator up to 5 days, or else they can be frozen for later use.