Preheat the oven to 350°F.
Sift the flour, baking soda, cinnamon, nutmeg, and salt into a mixing bowl. Set aside.
Place the butter and both sugars into the bowl of a stand mixer, fixed with a paddle attachment, and cream together (about 3 minutes).
Scrape down the sides of the bowl, add the egg and vanilla and continue to beat for another minute.
With the motor running on low, gradually add the flour mixture to the butter mixture and mix until just combined.
Fold the oats and chocolate chips into the cookie dough until fully combined.
Chill the cookie dough in the refrigerator for 30 minutes.
While the cookie dough chills, make the cream filling: Place the butter and shortening in the bowl of a stand mixer and cream together.
With the motor running, add the powdered sugar to the butter mixture, 2 tablespoons at a time. Scrape down the sides of the bowl.
Add the cream and vanilla and continue to beat until smooth. Set aside until ready to use.
With clean hands, roll out 48 (nickel sized) balls and place onto two parchment lined sheet pans.
Bake the cookies for 12 to 15 minutes or until golden brown.
Allow the cookies to cool for a couple of minutes before transferring them to a cooling rack and allow to cool completely.