Preheat the oven to 350°F.
Line a standard 12-cup muffin tin with paper liners or lightly grease with oil.(Note: I still like to spray the liners with avocado oil, olive oil, or coconut oil to prevent from sticking.) In a medium bowl, whisk together the pumpkin purée, eggs, applesauce* (adjust if using mashed banana add-in), oil, vanilla, and any optional add-ins such as mashed banana, maple syrup, or collagen. Mix until smooth and slightly frothy.
In a separate large bowl, combine the oat flour, almond flour, ground flaxseed, baking powder, baking soda, cinnamon, pumpkin pie spice, and salt. Stir well to evenly distribute the dry ingredients.
Pour the wet ingredients into the bowl with the dry ingredients. Use a spatula to fold the mixture together until just combined. The batter will be thick—avoid overmixing to keep the muffins light.
Divide the batter evenly among the 12 muffin cups, filling each about ¾ full. If desired, sprinkle hemp hearts on top or gently press a banana slice into the center of each muffin.
Bake for 28–32 minutes, or until the tops are golden and a toothpick inserted into the center comes out clean. If using mashed banana or maple syrup, extend the bake time to 30–34 minutes.
Remove the muffins from the oven and let them cool in the pan for 5 minutes. Carefully transfer to a wire rack to cool completely before serving. Enjoy!