Preheat oven to 350 degrees. Grease bottom and sides of muffin pan thoroughly, then dust with flour, tapping out the excess.

Whisk the flour, sugar, baking soda, and salt in a large bowl. Set aside.

Mix the mashed bananas, yogurt, eggs, butter and vanilla extract with a spoon in a medium bowl. Lightly fold in banana mixture into the flour dry ingredients with a rubber spatula until just combined. Add the chocolate chips and lightly stir until the batter is thick and chunky. Using a 1/4 cup measuring cup, pour batter into muffin pan.

Bake for 30 minutes until the muffins are golden brown and a toothpick inserted in the centers comes out clean. Cool in pan for 2 minutes, then transfer to a wire rack..