Preheat the oven to 375 degrees. Line a muffin tin with cupcake liners and set aside.

In a large bowl cream together the butter and sugar.

Add in the eggs and vanilla and mix well.

In a medium bowl combine the flour, baking powder, and baking soda.

Add the flour mixture to the butter mixture and mix well to combine.

Stir in the mashed bananas and mix well.

Gently fold in the blueberries so that they do not get smashed.

Using a large cookie scoop (1/4 cup), fill each of the muffin cups 3/4 of the way full.

Bake for 20-23 minutes or until the tops are golden brown.

Remove from the oven and cool completely on a wire cooling rack.