Preheat an oven to 350 degrees and add paper liners to a 12-cup muffin pan.
Add the mashed bananas, pumpkin puree, sugar, cinnamon, cardamom, eggs, vanilla extract, and soft butter into a large mixing bowl. Mix with a whisk or by hand until well combined.
Add the flour, baking powder, and baking soda, and salt and mix until combined.
Gently stir in the cinnamon chips and fold together until just combined.
Scoop the batter into the muffin tins, filling almost to the top.
Bake for 15-18 minutes or until a toothpick comes out clean. Don’t overbake!
Let the muffins cool for at least 15 minutes before serving.