Preheat oven to 350°F and line a muffin tin with 12 liners or spray with non-stick cooking spray. In a medium bowl, whisk together flour, pumpkin pie spice, baking powder, baking soda, and salt. Set aside.
In a large bowl of a standing mixer or handheld mixer, beat together butter and sugar. Add in the eggs and vanilla extract and beat until just combined.
Mash the ripe bananas either with a fork or in a blender, then measure out 1 cup. Only use one cup. If you are a little bit short, just top up the measuring cup with pumpkin puree to reach 1 cup.
Add the 1 cup of blended/mashed bananas and 1 cup pumpkin puree into the large mixing bowl and mix.
Add the dry ingredients into the bowl and mix until just combined, scraping the sides of the bowl every so often. Stir in the chopped chocolate or chocolate chips.
Scoop roughly ⅓ cup of the batter into each muffin liner, the liners should be about ¾ full. Sprinkle with more chocolate if desired.
Bake for 19-23 minutes or until a toothpick inserted in the middle of one of the muffins comes out clean. Remove from the oven and let the muffins cool in the muffin tray for 5 minutes, then transfer them to a cooling rack to cool completely.
BUTTER: Butter can be substituted with an equal amount of a neutral oil or unsweetened apple sauce.BANANAS: You can use bananas that have been previously frozen and thaw them out at room temperature before mashing, or you can use bananas that aren't frozen. Overripe bananas are best, and the more overripe they are the sweeter the muffins will be.PUMPKIN PUREE: Please note that this is not the same as pumpkin pie filling. Pumpkin pie filling has spices and sugar added into it, so it will affect the spice and sweetness of the muffins.PUMPKIN PIE SPICE: If you don't have pumpkin pie spice, you can use the following combination of spices: ½ tablespoon ground cinnamon, ½ teaspoon ground ginger, ½ teaspoon ground nutmeg, ¼ teaspoon ground cloves, and ¼ teaspoon ground allspiceMEASURING FLOUR: Properly measure your flour using the scoop and level method or a kitchen scale. OPTIONAL MIX INS: If you'd like, you can add chopped walnuts or pecans to the batter or sprinkle some on top before baking.Storage and Freezing Instructions: Store muffins for 2-3 days at room temperature in an airtight container.Freezing is my favorite way to have fresh muffins on demand! Freeze the cooled muffins in a ziploc freezer bag for up to 2-3 months. When ready to eat, take one out of the freezer and microwave it for 30 seconds (which makes them taste fresh out of the oven), or let it thaw at room temperature.