Preheat your oven to 350°F (175°C) and prepare a muffin tin either by lightly spraying it with cooking spray or by lining it with muffin liners.
In a mixing bowl, whisk together the following dry ingredients: flour, nutmeg, ginger, cinnamon, salt, baking powder, and baking soda. Set this mixture aside for now.
In a separate bowl or the bowl of a stand mixer, beat together the butter and sugar until they are well combined. Then, add the eggs and vanilla extract, continuing to beat until the mixture becomes smooth.
Now, incorporate 1 cup of blended or mashed bananas and 1 cup of pumpkin puree into the same mixing bowl, blending until well combined.
Gradually add the dry ingredient mixture into the bowl in 2-3 batches, mixing until just combined. Be sure to scrape down the sides of the bowl periodically to ensure even mixing. Avoid overmixing the batter.
Scoop the batter into each muffin liner, filling them to about ¾ full. If you desire, sprinkle some additional chocolate on top of each muffin.
Bake in the preheated oven for 20-22 minutes or until a toothpick inserted into the center of a muffin comes out clean.
Once done, remove the muffins from the oven and allow them to cool in the muffin tin for 5 minutes. Afterward, transfer them to a cooling rack to let them cool completely. Enjoy your freshly baked muffins!