Preheat oven to 375°F.
In a large mixing bowl mash the 4 medium bananas. Add in the eggs, oil, and sugar. Whisk to combine.
Sift the flour, baking soda, baking powder, and salt into the wet ingredients. Use a rubber spatula to mix batter until just combined. You should not see any dry flour at this point.
If using, add in the chocolate chips and mix until combined.
Spray a loaf pan with non-stick spray. Pour in the batter and let settle. Sprinkle the walnuts on top in an even layer.
Bake in the preheated 375°F oven until the top is dark golden brown, 50 minutes to an hour. You can poke the center of the loaf with a toothpick to check for doneness. If the toothpick comes out clean then the loaf is done!
Remove from the oven and let cool in the loaf pan for 20 minutes. To get the banana bread out of the loaf, gently flip it upside down onto a cutting board. Slice and enjoy!