Preheat oven to 350℉. Grease two 8-inch round pans (or three 6-inch rounds). Set aside.
In a large bowl, whisk together flour, cocoa powder, baking powder, baking soda, pumpkin pie spice and salt. Set aside.
In a separate bowl, vigorously whisk together sugar, pumpkin puree, vegetable oil, milk, eggs and vanilla until very well combined.
Pour wet ingredients into the bowl of dry ingredients. Mix just until combined. Stir in mini chocolate chips.
Transfer batter to prepared cake pans. Bake at 350 F for 20 to 25 minutes or until a toothpick inserted in the center comes out with little to no crumbs. Let the cakes cool in the pan for 10 minutes before inverting onto a wire rack to cool completely.
For the frosting, beat cream cheese and butter until smooth. Mix in pumpkin puree, followed by confectioners’ sugar, pumpkin pie spice and vanilla. Mix until creamy.
If necessary, level the cakes with a serrated knife. Frost the top of one cake layer and place the second cake on top (repeat if doing 3 layers).
Frost a crumb coat (thin layer of frosting) around the outside and top of the cake. Place the cake in the freezer for 30 minutes to set.
Use remaining frosting to frost the cake. Garnish with piped frosting, chocolate ganache or chocolate shavings.
Notes
Pumpkin pie spice: To make your own, whisk together 3/4 teaspoon cinnamon + 1/2 teaspoon ground ginger + 1/4 teaspoon ground nutmeg + 1/4 teaspoon ground allspice (or cloves). Cream cheese: Use full-fat block-style. It's thicker than other varieties so the frosting will have more structure.Store in an airtight container at room temperature for 2 days or in the refrigerator for 4 days.Freeze for up to 3 months. Wrap the cake (or slices) in plastic wrap and store in the freezer. Defrost in the refrigerator before bringing to room temperature and serving.