Preheat an oven to 180c (350f) and prep a 12-cup muffin pan with paper liners.
Into a big mixing bowl, add the mashed bananas, pumpkin puree, sugar, cinnamon, eggs, vanilla extract, kosher salt, and cooled melted butter. Mix with a whisk until the mixture is well combined.
Add the flour, baking powder, and baking soda, and mix until almost combined.
Add the chocolate chip and mix until just combined.
Pour the batter into the muffin tins filling almost to the top.
Make the streusel topping:
Into a medium mixing bowl, add the flour, sugar, cinnamon, and melted butter. Mix with a spoon until the mixture is well combined.
Top the muffins with about 1 tablespoon of the streusel topping and press the streusel topping onto the muffin batter so it sticks and does not fall off while baking.
Bake in a 180c (350f) preheated oven for 18-20 minutes or until a toothpick comes out clean. Don’t overbake these muffins! Let the muffins cool for at least 15 minutes before serving.
Notes
Use room temperature ingredients. It is important that you use room-temperature ingredients like eggs and milk. This step ensures that your mixture mixes into a homogenous mixture and bakes perfectly. you don’t want to place cold batter into the oven.
Don’t overmix the batter, you don’t want to develop the gluten in the flour. This step ensures you have moist muffins and not dense and dry muffins.
Use only ripe bananas for this recipe! ripe bananas are more sweet, moist, and easy to mash into a pudding consistency. If you don't have ripe bananas, bake regular bananas in a 200c (400f) preheated oven for 10 minutes, this will soften the bananas and make them into a ripe banana texture.
Mesure you flour correctly! When measuring your flour, avoid scooping it with a measuring cup. Instead, stir the flour with a spoon to create as many air pockets as possible, and spoon it into your measuring cup. Finally, level it with a back of a knife.
Use pure pumpkin puree in this recipe! It is very important that you use pure pumpkin puree in this recipe. Make sure that you are not using the presweetened or pre-spiced pumpkin puree. You will be able to find this information on the ingredient list of your pumpkin puree can.
Add some of your favorite add-ins! Make this recipe your own and add your favorite muffins add-ins: chocolate chips, chopped walnuts, chopped pecans, chocolate chunks, banana slices, chopped fruit, and more! Be creative!
Be patient! I know it's extremely tempting to eat these muffins as they are pulled out of the oven, but let these muffins cool for at least 15 minutes so they will be more firm and won't crumble up. These muffins are extra moist and melt in your mouth delicious, so it will be worth it to wait these 15 minutes.