Preheat oven to 350 degrees.
In a medium bowl, whisk together the oat flour, baking powder, baking soda, salt, pie spice, and stevia.
In a large bowl, mix the sugar with the wet ingredients (pumpkin, eggs, vanilla, milk).
Stir everything together until smooth and well combined.
Oil or butter 18 muffin cups VERY WELL. These stick to paper muffin cups, so I don't recommend using them.
Divide the batter equally among the muffin cups (I got about 18 good-sized cupcakes).
Bake the cupcakes for 15-18 minutes, until a toothpick comes out clean.
Cool the cupcakes for about 10-20 minutes (they will sink in the middle a bit).
Top with whipped cream and enjoy!