Place oven rack in the lowest position.
Preheat oven to 350°F.
Grease only the bottom of a 9x5 loaf pan. This prevents the loaf from developing a ridge around the edge.
Mash three ripe bananas. This should yield one cup.
In a small mixing bowl, combine dry ingredients.
In a large mixing bowl, mix sugar and oil together. Add eggs and beat until smooth. Then mix in yogurt and mashed bananas.
Add dry ingredients and stir until just combined.
Gently stir in nuts or chocolate chips, if adding.
Pour into prepared loaf pan.
Bake at 350°F for 60-75 minutes, or until toothpick inserted in center comes out clean.
Cool in pan on a wire rack for 15 minutes, before turning out onto the rack to cool completely. You may need to loosen the edges with a knife.