Preheat the oven to 350°F (175°C). Lightly spray a muffin tray with non-stick cooking spray or line with muffin liners. Set aside.
Prepare the dry ingredients: In a medium-sized mixing bowl, whisk together the all-purpose flour, whole wheat flour, ground flax/chia seed blend, baking soda, baking powder, salt, and ground cinnamon. Set aside.
Combine the wet ingredients: In a separate large mixing bowl, whisk together the eggs, milk, maple syrup, melted butter or coconut oil, vanilla extract, pumpkin puree, and mashed banana until smooth.
Mix the dry ingredients with the wet: Gently fold the dry ingredients into the wet ingredients, being careful not to overmix. If desired, fold in the chopped nuts.
Fill the muffin tray: Divide the batter evenly between 12 prepared muffin cups. If desired, sprinkle the tops with additional chopped nuts or rolled.
Bake: Place the tray in the oven and bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Cool and serve: Let the muffins cool in the tray for 5 minutes before transferring to a wire rack to cool completely. Enjoy!