Whisk the flour, baking powder, spices, and salt together in a medium bowl. Add the milk, pumpkin, and melted butter. Stir with a fork until just combined. Let sit five minutes to “develop” (just a fancy word for letting the baking powder activate).

Meanwhile, heat your waffle iron. Pour, or ladle, enough batter to cover about 2/3 of the surface (the rest will spread once you close the top). Most waffle irons have a light that goes on or off, signaling the waffles are ready. A sure sign of doneness is once you see all the steam has stopped shooting out the sides, too.