Preheat oven to 375°F. Line a 12-cup muffin pan with parchment or cupcake liners, or lightly grease with cooking spray. Set aside.
Puree oats in a blender or food processor until they reach a flour-like consistency. Add in the pumpkin pie spice, baking soda and sea salt, and pulse until the mixture is evenly combined. Set aside.
In a separate large mixing bowl, whisk together the eggs, milk, pumpkin puree, maple syrup, coconut oil and vanilla extract until evenly combined. Fold the dry ingredients in with the wet ingredient mixture, and stir until the mixture is just combined. (Try to avoid over-mixing.)
Portion the ingredients into prepared baking cups. Then sprinkle a pinch of turbinado sugar on top of each muffin, if you would like.
Bake for 15-18 minutes, or until a toothpick inserted in the center of the muffins comes out clean. Remove from the oven and place the pan on a cooling rack for 5 minutes.
Serve warm. Or let the muffins cool to room temperature, then store in a sealed container for up to 3 days, or freeze for up to 3 months.