Preheat oven to 350°F. Place mini cupcake wrappers into mini muffin pan; set aside.
Add flours, chia seeds, cinnamon, salt, and baking soda to a mixing bowl and stir until well combined.
In a separate bowl, mash banana with a fork. Add egg, coconut oil (melt, if needed), milk, and vanilla; whisk together.
Gradually add wet ingredients to the dry, mixing until just combined. Fold in chopped pecans.
Pour an even amount of batter into each muffin cup. Bake for 15 minutes or until a toothpick inserted comes out clean.