Preheat oven to 350 degrees.
In a medium size bowl, stir flour, baking powder, salt, sugar and spice and set aside.
In a smaller bowl, stir pumpkin, milk, melted butter and vanilla together to combine. Pour wet ingredients into dry ingredients and mix to create a thick batter. Pour into an 8-inch casserole dish with high sides.
In a separate bowl, stir sugar, brown sugar and pecans together. Spread evenly over batter. Pour hot water over the entire thing (without stirring) and bake for 40 minutes or once the middle is set. (Place a baking sheet under in case it bubbles over.)
Cool 5–10 minutes before serving. Serve warm with vanilla ice cream.