Preheat the oven to 400 degrees F and line a 12-cup muffin pan with paper liners.
Mix the flour, baking powder, baking soda, and salt in a large bowl and set aside.
Combine the sugar, melted butter, and mashed bananas in a medium bowl and whisk together until smooth. Next, add the eggs and vanilla and whisk until well combined.
Pour the wet ingredients into the dry. Fold together until almost mixed, but streaks of flour still show.
Add the chocolate chunks and finish mixing until the chunks are evenly distributed and no more streaks of flour remain. The batter will be a little thick, do not over mix.
Divide the batter among 12 lined muffin cups. The muffin cups will be full, and that's what you want for bakery-style muffins.
Bake at 400 degrees F for 15-18 minutes until the muffins are golden brown, risen in the center and a toothpick inserted comes out clean.