Preheat oven to 350 degrees.
Line cookie sheets with parchment paper.
In a large bowl whisk together the flour, baking powder, baking soda, salt, and spices.
Add the oats. Stir to mix together.
Using the electric mixer add the butter beating until it is light and fluffy. Continue beating as you add in both sugars. Beat for 2 minutes. (Or until fluffy)
Add the pumpkin, egg yolk, and vanilla. Mix until well combined. Slowly add the flour mixture. Mix until just combined.
To form the cookies use a cookie scoop. Scoop cookie dough and roll it into a perfect ball with your hands.
Put the cookie balls (2 inches apart) on the cookie sheet.
Flatten the cookie balls into flat cookies using 2 fingers.
Bake at 350 degrees for 9-10 minutes. (Or until the cookie edges turn golden brown)
When the cookies are done take out of the oven.
Set the cookies on the cookie sheets aside for cool for 5 minutes.
Transfer the cookies to a cooling rack.