In a medium bowl, mix the flour, baking powder, salt, granulated sugar, and spices together. Set it aside for a moment.
In another bowl, blend the pumpkin puree, milk, melted butter, and vanilla until smooth. Pour this mixture into the dry ingredients and stir just until combined to make a thick batter.
Transfer the batter to an 8-inch casserole dish, making sure the sides are high.
In a separate bowl, combine the remaining granulated sugar, brown sugar, and chopped pecans. Sprinkle this mixture over the batter evenly.
Carefully pour the hot water over the entire dish without stirring anything! Bake it for about 40 minutes, or until the center is set. Place a baking sheet under it just in case it bubbles over.
Let it cool for 5-10 minutes before serving. Enjoy it warm with extra pecans and a scoop of vanilla ice cream!