Preheat the oven to 350°F and line a muffin tin with 12 liners.
In a medium mixing bowl, whisk together the oat flour, baking powder, baking soda, salt, pumpkin pie spice, and cinnamon. Make sure all the clumps are removed, and then set it to the side.
In another mixing bowl, whisk together the eggs, pumpkin puree, maple syrup, melted coconut oil, and vanilla extract.
Make homemade oat flour: in a blender, add 1.5 cups of rolled oats, and blend on high for 45 seconds or until a "flour" consistency. Should make about 1 cup of oat flour.
Add in the dry ingredients and mix until combined and there are no lumps of flour. Fold in the chocolate chips, walnuts, or pecans.
Then, fill each muffin liner with batter until about ⅔ full. Feel free to sprinkle extra chocolate chips, pecans, or walnuts on top before baking.
Bake for 18 – 22 minutes or until a toothpick comes out clean. Let the muffins cool before enjoying them!