Gather all you ingredients.
Preheat oven to 425.
In a large bowl add flour, baking powder, baking soda, salt, cinnamon, and brown sugar.
With your second bowl, you will add butter, eggs, milk, and vanilla. Mix around well.
Add the wet mixture of eggs into the dry mixture.
Peel the bananas and then mash them with a fork on a plate. Add the bananas to your batter, and then mix everything together.
Add the raisins and mix them in.
Next, line a muffin pan with muffin liners.
Take a spoon and fill the liners with the batter all the way to the top.
Place the muffins in the oven and bake for 5 minutes at 425, then reduce heat and continue cooking for an additional 15 minutes at 350. To check if done insert a toothpick in the center and see if it comes clean.
Let the muffins cool for 10 minutes and then enjoy.