Preheat the oven to 350°F and grease a 9- or 10-cup bundt cake pan with cooking spray.
In a large bowl, whisk together one box of cake mix with 1/2 cup vegetable oil, 1 cup water, 3 large eggs and 1/3 cup sour cream. Pour the batter into the prepared cake pan and bake until a toothpick inserted comes out clean, about 35 minutes.
Remove the cake from the oven and let it cool completely in the pan. Once the cake has cooled, invert it onto a serving platter, clean out the pan, and repeat the mixing and baking process with the remaining box of cake mix, vegetable oil, water, eggs and sour cream.
To assemble the cake, arrange the second cake on top of the first to form a pumpkin shape. (If needed, trim the bottom portions of the cakes to make them flat.)
Add about 3 tablespoons of the frosting to a small bowl then tint it green with food coloring. Spread the green food coloring on the ice cream cone then decorate it with sprinkles.
Add the remaining frosting to a microwave-safe bowl then tint it orange with food coloring. Microwave it until pourable, about 30 seconds.
Pour the orange frosting atop the completely cooled cakes then place the ice cream cone in the center to form the pumpkin stem.
Cut the cake into slices and serve.
★ Did you make this recipe? Don't forget to give it a star rating below!