Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan with butter or cooking spray, then lightly dust with flour, tapping out any excess.

In a large mixing bowl, mash the overripe bananas with a fork until mostly smooth with just a few small lumps remaining. Stir in the melted butter until well combined.

Add the brown sugar, beaten egg, vanilla extract, and Greek yogurt to the banana mixture. Stir until everything is well incorporated.

In a separate bowl, whisk together the flour, baking soda, and salt. Add the dry ingredients to the wet ingredients and gently fold together until just barely combined - don't overmix.

Fold in the chocolate chunks, reserving a few tablespoons to sprinkle on top of the batter if desired.

Pour the batter into the prepared loaf pan and spread evenly. Sprinkle the reserved chocolate chunks on top.

Bake for 60-65 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs attached. If the top browns too quickly, tent with foil during the last 15 minutes.

Cool in the pan for 10 minutes, then turn out onto a wire rack to cool completely before slicing. This helps maintain the perfect texture.