Begin by mashing the ripe bananas in a large mixing bowl until they are smooth and pureed. Use a fork or potato masher to achieve the desired consistency.
Add in the melted margarine, milk, and lightly beaten eggs to the mashed bananas. Mix well until all of the wet ingredients are incorporated.
In a separate mixing bowl, combine flour, baking soda, baking powder, sugar, and salt. Gradually add this dry mixture to the wet ingredients and mix until just combined.
Gently fold the chopped nuts to the batter. Be careful not to overmix as this can result in tough bread.
Grease a 9×5 inch loaf pan with non-stick spray and pour the batter into it. Smooth out the top with a spatula for an even bake.
Bake at 350°F for 50-60 minutes or until a toothpick inserted in the center comes out clean. Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slice and serve as desired.