Heat oven to 350 degrees F. Grease muffin tin with butter or baking spray and lightly flour.

In bowl of stand mixer, or medium mixing bowl, whisk together flours, baking powder and baking soda, salt. On low speed, add butter and mix until well-blended, about 30 seconds.

Add bananas, sugar and beat until incorporated. Add vanilla extract and eggs, one at a time; beat on medium for another 20-30 seconds. Gently stir in blueberries.

Fill muffins cups to 3/4 full and bake about 22 minutes until golden brown and center springs back when lightly touched.

Let cool on rack for 10 minutes before carefully removing muffins.