Preheat the oven to 350 degrees Fahrenheit. Spray a 9 x 13 x 2-inch baking pan with nonstick cooking spray and set aside.
Add 1 (15.25-ounce) spice cake mix and 1 (15-ounce) can pumpkin puree to a large bowl and mix together until smooth and combined. The batter will be quite thick.
Spread the batter evenly into the prepared pan. Bake for 22-25 minutes, until a toothpick comes out clean when inserted into the center of the cake.
Let the cake cool completely before topping with your desired topping and serving.
Notes
Storage Instructions:
Room Temperature: Store the cake in an airtight container at room temperature for up to 3 days.
Refrigerator: Keep in the fridge for up to 5 days in an airtight container.
Freezer: You can freeze unfrosted cake for up to 3 months. Let the cake cool completely, then freeze for a couple of hours until firm. Wrap in 2–3 layers of plastic wrap and then a layer of heavy-duty aluminum foil. Thaw at room temperature for 2–3 hours or until fully defrosted when you're ready to eat.