Preheat oven to 375 degrees F (180 degrees C). Spray a loaf pan with cooking spray and line it with parchment paper. This will make it easier to pull out the bread later.
In a medium bowl, mix the flour, baking powder, baking soda, salt, and cinnamon together.
In a large bowl, mash the bananas until there are no chunks left. Mix in the eggs, sugar, peanut butter, oil, applesauce, and vanilla. Gradually mix in the flour mixture. I usually add the flour in 3 batches. Divide the batter into two bowls.
Melt the chocolate chips in the microwave. Start by heating it for 30 seconds, then continue heating it in 15-second intervals until nearly all the chips have turned glossy. Pull the chips out of the microwave, and stir until you get a creamy chocolate mixture. Mix the chocolate with one half of the batter.
Pour the batter into the loaf pan, alternating between the light and dark batters. Using a knife, toothpick, or a skewer, swirl the batter on the top. You don't need to overwork it, but you just want to create a bit of a pattern.
Bake for 55 to 60 minutes, or until a toothpick comes out clean. Let the bread cool for 10 minutes before pulling it out of the pan.
PREPARE THE PECAN PRALINE: In a small saucepan, melt the butter. Then add sugar and milk, and mix everything together until everything looks like a sauce. Turn off the heat, and stir in the vanilla and pecans. Pour the sauce over the bread. The praline hardens pretty quickly. If the sauce hardens before you poured it on top of the bread, just reheat it.
Wrap leftovers in foil and refrigerate. It should keep for at least a week.