To begin, preheat your oven to 350 and spray a muffin pan with non-stick spray.
To a small mixing bowl, add your flour, baking powder, baking soda, salt and pumpkin pie spice and stir them together.
To a large mixing bowl, add your butter and brown sugar and beat them together with a mixer till creamy. Add your banana, pumpkin puree and vanilla and mix together again. Last, add your eggs and briefly blend them in.
Add your dry ingredients to your wet ingredients and stir together till you have a smooth muffin batter. Scoop into your muffin tin, filling each cavity about 2/3 full with batter.
Bake in the oven for 20-22 minutes, or till the muffins are springy to touch and a toothpick inserted comes out clean.
Let cool, then devour!
Stored in an airtight container in the fridge, these muffins last about a week.