Preheat oven to 350 degrees and get your muffin pan ready. I use a 24 mini muffin pan
Melt the butter and let it cool. Set aside
In a large mixing bowl, mash the banana using the fork and proceed to whisk an egg
Add the melted butter, vanilla, egg, sugar, salt and baking soda to the mashed banana
Lastly, add the flour and give it a stir with the spatula until all ingredients are well combined
Using a small spoon or a measuring spoon, fill up each muffin cup with the batter.
Insert the chocolate chunk pieces and bake for about 20 minutes or until a toothpick comes out clean
Remove from the oven and let them cool before serving. Enjoy!