Preheat the oven to 350°F.

In a large mixing bowl, combine the bananas, sugar, eggs, vanilla, and melted butter until smooth.

Gradually stir in the flour and chia seeds, then fold in the chocolate chips until just combined.

Fill a mini muffin pan ¾ full.

Bake for 15 minutes, or until a toothpick inserted in the center comes out clean.

Let cool slightly before serving.