Preheat oven to 350 degrees F. Lightly coat four 5 3/4-inch mini loaf pans with nonstick spray.

In a large bowl, combine flour, baking powder, baking soda and salt.

In the bowl of an electric mixer fitted with the paddle attachment, beat butter and sugar on medium-high until light and fluffy, about 2-3 minutes. Beat in eggs, buttermilk and vanilla until well combined. Beat in bananas until well combined. Gradually add flour mixture to the sugar mixture at low speed, beating just until incorporated.

Add blueberries and gently toss to combine.

Scoop the batter evenly into the loaf pans. Place into oven and bake for 30-35 minutes, or until a tester inserted in the center comes out clean.

Remove from oven and let cool for 15 minutes before inverting the cake onto a wire rack.