Preheat oven to 350 degrees Fahrenheit and lightly grease a 9" pie plate or baking dish and set aside.
In a large bowl, stir together the flour, 3/4 cup brown sugar, baking powder, cinnamon, salt, nutmeg and cloves with a spoon.
Add in pumpkin, milk, oil and vanilla and stir until a thick batter forms. Spread evenly into prepared pie plate.
In a small bowl, stir together 1 cup brown sugar and corn starch until there are no clumps. Sprinkle over cake batter.
Add butter to hot water and stir until melted. Pour over brown sugar mixture in pan.
Bake for 35-40 minutes until top is completely set (keep in mind that there is a thick layer of caramel sauce in the bottom, so it may jiggle). Let sit for 5-10 minutes before serving.
Leftovers can be stored in the refrigerator and reheat perfectly!