Preheat oven to 350 degrees F. Place the oven rack in the center of the oven. Line a 12 cup muffin pan with paper liners or lightly butter or spray the muffin cups with a vegetable spray.
In a small saucepan melt the butter. Let cool to room temperature.
In a medium sized bowl whisk together the eggs, vanilla extract and mashed banana. Add the melted butter and stir to combine.
In another large bowl combine the flour, sugar, baking powder, baking soda, cinnamon, and salt. Gently fold in the berries, making sure they are coated with flour. (This helps to prevent the berries from sinking during baking.) Add the wet ingredients to the dry ingredients and stir only until the ingredients are just combined. Do not over mix the batter or tough muffins will result.
Divide the batter evenly among the 12 muffin cups, using two spoons or an ice cream scoop. Place in the oven and bake until a tester inserted in the center of a muffin comes out clean, about 20 to 25 minutes. Transfer to a wire rack to cool. Can be stored for a few days at room temperature.
by The Savvy Kitchen