Preheat oven to 325 degrees F.

Mash bananas with a fork.

Soften butter in a microwave. FYI - I like to melt the butter for better mixability.

Lightly beat the eggs.

Stir mashed bananas, melted butter (or oil), eggs and cake mix together.

Optional - After mixing batter, add mini chocolate chips or chopped nuts to the batter. Stir batter until chocolate chips or nuts are completely mixed in.

Pour finished batter into a nonstick bread pan. Smooth out the top of the batter within the bread pan.

Bake in the oven at 325 F for 65-70 minutes.

Take out of oven and let the banana bread cool down in the bread pan for 10 minutes. Do not remove the banana bread from the bread pan during this 10 minute cool down period. Use oven mitts as the bread pan will be very hot coming out of the oven.

After 10 minutes, remove the banana bread from the bread pan. Place the banana bread on a cooling rack in order to completely cool. This cool down may take 1-2 hours. Gently slide a silicon spatula between the banana bread and the bread pan walls if the banana bread is stuck in the pan.