Add the oat flour, baking powder, baking soda and pumpkin pie spice to a large mixing bowl and mix well.
Add the soy milk, dates, vanilla and pumpkin puree to a blender and blend until the dates are pulverized.
Pour blender mixture into the flour mixture and stir well.
Scoop batter into a piping bag.
Pipe out 12-16 cookies onto a parchment lined baking tray.
Bake for 15 minutes.
Once baked carefully place cookies onto a cooling rack to cool for 10 minutes.
Add the frosting ingredients to a blender and blend until smooth.
Frost cookies with frosting.
Don't stack frosted cookies. Keep in an airtight container in the refrigerator for at least a week.