Preheat oven to 375 degrees F. Spray a muffin pan with non-stick cooking spray, set aside.
In a medium bowl, whisk together the flour, baking powder, baking soda and salt; set aside.
In a large bowl, cream together the butter and brown sugar with a handheld mixer. Add in eggs, one at a time making sure that both eggs are incorporated. Mix in vanilla extract and mashed bananas.
Add the flour mixture in 2 parts alternating with the buttermilk and ending with the flour mixture.
Stir in raspberries, making sure to not over mix or the color will bleed.
Fill prepared muffin pan 2/3 cup full or two heaping tablespoons.
Bake for 20-22 minutes, or until toothpick inserted into the center comes out clean.
Place on cooled oven and let sit for 10 minutes.
Using a spoon or butter knife, lightly run it along the edges to remove muffin. Place on a wire rack and cool.
Eat immediately and enjoy!