Preheat oven to 3425 degrees F (175 degrees C). Coat muffin pans with non-stick spray, or use paper liners.
Sift together the flour, baking soda, brown sugar, and cinnamon.
Combine bananas, oil, milk, eggs, salt, and vanilla in a large measuring cup or bowl with spout.
Make a small well in the center of the dry ingredients. Pour wet ingredients into the center and stir until just moistened, but still lumpy. Do not over mix.
Stir in nuts. Divide into muffin tins.
Put in oven and immediately reduce temperature to 375. Bake until golden brown, about 25 minutes. Rotate pan halfway through cooking. Check for doneness with toothpick.