Preheat the oven to 350 degrees. Spray 2 8-inch round cakes pan with cooking spray. Line the bottom of the pan with parchment and spray the parchment with cooking spray Lightly dust with flour and set aside.

Whisk the flour, baking powder, baking soda, salt, and spices together in a medium mixing bowl.

In another large mixing bowl, combine the oil, eggs, sugars, pumpkin, sour cream, and vanilla. Beat with an electric mixer set to medium speed until smooth.

Use a rubber spatula to fold the flour mixture into the pumpkin mixture until smooth. Pour half of the batter into one of the prepared pans and set aside.

Sift the cocoa powder over the remaining pumpkin batter and add the whole milk. Fold the cocoa powder into the cake batter until incorporated and pour into the second pan. Bake 35 to 40 minutes, until a cake tester inserted into the center of the cake comes out clean.

Cool for 20 minutes in the pan, then carefully invert onto a wire rack to cool completely before assembling your cake.

Place the butter in a large mixing bowl and beat with an electric mixer until smooth.

With mixer on low, gradually beat in 5 1/2 cups of the powdered sugar, the cocoa powder, 6 tablespoons milk, and the salt. Turn mixer to medium and beat until well combined, stopping the mixer occasionally to scrape the sides and bottom of the bowl.

If frosting is too thin, add additional powdered sugar; it it’s too thick add additional milk.

Use a long serrated knife to split each cake layer into two layers.

Set one of the chocolate cake layers on a cardboard cake circle or a cake stand and spread an even layer of frosting over the top. Top with a pumpkin layer and more frosting. Continue like this until you’ve used all the cake layers.

Use the remaining frosting to frost the cake. Decorate as desired and serve.