Preheat oven to 350°F. Spray a 9-inch cake pan with cooking spray, or line the bottom of the pan with a piece of parchment paper and set aside.

In a large mixing bowl, cream the butter until light and fluffy with an electric mixer. Add the egg and vanilla extract and mix until well combined. Add both packages of Martha White© Apple Cider Muffin Mix. Mix until dough comes together. Stir in the pecans. 

Spread the dough into the prepared pan, using your clean hands or a spatula to help press out and evenly fill the pan. Bake 20-25 minutes or until the edges are golden brown and the cookie cake is cooked through.

Remove cookie cake from the oven and place on a wire rack to cool completely in the pan.

While the cookie cake is cooling, prepare the frosting by creaming the butter in a mixing bowl. Add the remaining ingredients and mix until combined, stopping the machine and scraping down the sides of the bowl at least once, then continuing to mix until the frosting is light and fluffy.

Carefully run a butter knife around the outside edge of the cookie and carefully remove it from the pan. Place on a serving plate. Decorate with Apple Cider Buttercream Frosting.