Preheat your oven to 350°F (175°C) and grease a 9-inch springform pan. In a mixing bowl, beat the cream cheese until smooth for about 2-3 minutes. Gradually add in the granulated sugar and flour, mixing well. Stir in the vanilla extract, cinnamon, and heavy whipping cream, blending until creamy. Incorporate the eggs one at a time, ensuring a smooth mixture. Pour the cheesecake batter into the prepared pan and bake for 10 minutes. Lower the oven temperature to 200°F (95°C) and bake for an additional 30-35 minutes. The edges should set but the center will slightly jiggle. Turn off the oven and let the cheesecake cool gradually for 30 minutes before chilling it in the fridge overnight.

While the cheesecake chills, preheat your oven to 350°F (175°C) again and grease a 9-inch cake pan. In a large bowl, whisk together the flour, baking powder, and spices until combined. In another bowl, cream the butter and brown sugar together until light and fluffy, about 4-5 minutes. Add the vegetable oil, egg, and vanilla extract, mixing well. Gradually incorporate the dry mixture into the wet ingredients, alternating with the milk, and mix until just smooth. Pour this spiced batter into the greased pan and bake for 15-17 minutes, or until a toothpick comes out clean. Allow the cake to cool completely before refrigerating it overnight.

To create a delightful frosting for your Thanksgiving Piecaken, beat the softened butter in a mixing bowl until it’s fluffy, about 3-4 minutes. Gradually sift in the powdered sugar and mix until incorporated. Then add the ground cinnamon, vanilla extract, and heavy cream, whipping the mixture until it becomes light and creamy. Taste and adjust the sweetness by adding more powdered sugar if desired. Set your frosting aside for assembly later.

Once your layers are fully chilled and set, it's time to assemble the Thanksgiving Piecaken. Carefully trim each layer with a serrated knife to ensure they are uniform in size. Place the cheesecake layer upside down on a serving stand or plate. Evenly spread a layer of frosting on top of the cheesecake, then place the spice cake layer on top. Frost the top of the spice cake, then trim the crust off the store-bought pumpkin pie and place it directly on top. Cover the entire cake with the remaining frosting for a beautiful finish.

After the cake is fully assembled, chill it in the refrigerator for at least 1 hour to allow the frosting to set. Once set, you can smooth out any uneven frosting and decorate as desired with additional cinnamon or even festive sprinkles. Slice and serve your Thanksgiving Piecaken chilled to reveal its decadent layers, impressing friends and family alike!