Preheat oven to 350°F. Grease a 9 x 13-inch baking dish; set aside.
MAKE THE FILLING AND STREUSEL:
Combine brown sugar, cinnamon and salt in a large bowl. Set aside ½ cup of this brown sugar mixture for the filling. Stir the flour into the remaining brown sugar mixture. Add melted butter and mix until completely combined and no dry pockets remain. The mixture should form little clumps. Set aside while you prepare the cake.
MAKE THE CAKE:
Beat cake mix, dry pudding mix, pumpkin, oil, water, eggs, cinnamon, cloves, nutmeg and ginger in a large bowl with an electric mixer on low speed just until moistened, scraping the sides of the bowl frequently. Beat on medium speed for 2 minutes, or until well blended.
Pour about half of the batter into the prepared baking dish; spread in an even layer. Sprinkle the reserved brown sugar filling mixture evenly over the batter. Dollop the remaining batter evenly over the filling and spread to the edges of the pan with an offset spatula. Crumble the streusel into pea-size crumbs evenly over the top layer of batter.
BAKE THE CAKE:
Bake the cake in the 350°F for 35-45 minutes, or until a toothpick inserted in the center comes out clean. Cool in pan on a wire rack for 30 minutes. Cut into squares and serve warm, or cool completely before slicing and serving.
Cake can be stored in an airtight container at room temperature for up to 3 days, or in the refrigerator for up to 1 week.
Notes
Make sure that you use just 1 cup (not an entire can) of the pumpkin puree. This is 100% pure pumpkin, not the canned pumpkin pie filling.
The total baking time will vary depending on your individual oven, as well as the type of pan that you use. Dark or nonstick pans bake the cake faster, while a glass or light-colored dish will need a bit more time. Use a toothpick inserted deep into the middle of the cake to know exactly when it's done.
Once cool, dust the top of the cake with powdered sugar or drizzle with vanilla glaze for a special touch.
The moist cake gets better as it sits, so this is a nice breakfast or dessert option to prepare the day before you plan to serve it.