In a large bowl whisk together the pumpkin, milk, eggs, brown sugar and pumpkin spice. Pour mixture into prepared pan.
Dump the cake mix over the pumpkin mixture. Then slice the butter into thin pieces (about 24 pieces) over the top. I place 6 rows of butter across the top and 4 down, so it melts evenly. Top with nuts or graham crackers if desired.
Bake for 45 minutes or until the center is set and the edges are golden brown. Remove from oven and allow to cool atleast 10 minutes before serving.
Serve with vanilla ice cream or whipped cream if desired.
Notes
More variations:
Peach: Use 2 cans undrained sliced peaches in heavy syrup. Or use 1 can sliced peaches and 1 can crushed pineapple.
Apple: Use 2 cans apple pie filling and top with chopped nuts. You can also use homemade apple pie filling if preferred.
Blueberry: Use 2 cans blueberry pie filling or 4 cups fresh blueberries + 1/2 cup sugar.
Crockpot method: Pour the fruit in the bottom of the crockpot. Dump the cake mix on top and add the sliced butter. Cook on low for 3-4 hours or on high for 2-3 hours. Dutch oven method for camping: Line the pan with foil and spray with nonstick spray. Add the fruit filling, then pour the cake mix on top and then the sliced butter. Cover with lid and cook on hot coals for about 30 minutes.