In a large bowl, combine the flour, baking powder, and salt.
In another bowl, mix the bananas, yogurt, and sodium bicarbonate.
Let it sit until the mixture has risen.
In a third bowl, mix the egg, sugar, oil, and vanilla.
Using a wooden spoon, incorporate the banana mixture into the egg mixture.
Pour this mixture over the dry ingredients and mix until the dough is moist but not too much (the dough will be lumpy).
Stir in the chopped chocolate.
Put the dough in a lightly oiled 9×5 inch (23 cm x 13 cm) loaf pan.
Bake in a preheated oven at 350 F (180 C) for 50 to 60 minutes, or until a toothpick inserted in the center comes out clean.
Let the pan cool on a wire rack for 10 minutes.
Remove the bread from the pan and let it cool completely. (You can prepare the bread ahead of time, slice it if desired, and wrap it in plastic wrap. It will keep for up to 1 week in the refrigerator or up to 2 months in the freezer, placed in a freezer bag.)