Preheat the oven to 350ºF. Spray a 9" round cake pan with baking spray. Line with parchment paper if desired so that you can pull out the cookie cake to get pretty slices.
In a medium-size bowl, use a spoon or a hand mixer to combine the sugars and butter. Add in the pumpkin and mix well. 1/4 cup light brown sugar, 1/4 cup white sugar, 1/2 cup salted butter, 1/2 cup solid-pack pumpkin puree
Add the salt, cinnamon, pumpkin pie spice and baking soda and mix until combined. Add the flour and mix just until combined. The batter will be thick. 1/4 teaspoon salt, 1/2 teaspoon ground cinnamon, 1 teaspoon pumpkin pie spice powder, 1/2 teaspoon baking soda, 1 1/2 cups all-purpose flour
Lastly, fold in the cinnamon chips. 3/4 cup cinnamon chips
Spread the pumpkin batter evenly on the bottom of the prepared pan. Sprinkle the chopped pecans on top of the batter and press down lightly with your hand so they stick in the batter. 1/4 cup chopped pecans
Bake the cookie for 20-23 minutes, until it is cooked through.
While the cookie pie is cooling, prepare the buttercream. In a small bowl, use an electric mixer to cream the butter for 2-3 minutes. It should get creamy and whitish in appearance. 1/2 cup salted butter
Add in the vanilla, cinnamon and powdered sugar and mix well. Pour in 1-2 tablespoons of heavy cream and whip the frosting again, until the buttercream is the texture you would like it. 1/2 teaspoon vanilla extract, 1/2 tablespoon ground cinnamon, 1 cup powdered sugar, 1-2 tablespoons heavy cream
Use a decorating bag with a large tip (Wilton 1M or 2D) to decorate the edges of the cake.
Notes
Store at room temperature in an airtight container.The calories shown are based on the pie being cut into 8 pieces, with 1 serving being 1 slice of pie. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. *We are not dietitians and recommend you seek a nutritionist for exact nutritional information.*