Melt the butter and set aside.
In a large mixing bowl, vigorously whisk together the egg, pumpkin puree, and sugar until blended and smooth. Add the vanilla and melted butter and whisk until combined.
Combine the flour, baking powder, salt and pumpkin pie spice, and sift together over the large mixing bowl containing the egg mixture.
Fold the ingredients together with a spatula until combined.
Preheat your pizzelle iron to medium-high heat or until a drop of water sizzles on the cooking surface. On my pizzelle iron these did best on about level 4.
Scoop the batter into a large zip lock bag or pipping bag. Cut the corner of the bag into a 1/2" opening.
Pipe about 1 tablespoon of batter into the center of the iron and cook according to your manufacturer directions. If they are too big for your press, pipe a little less next time. It may take a few tries to get them just right but I have found that centering the batter is the key to a good shape.
Remove the hot pizzelles to a wire rack covered with parchment paper to cool. Store at room temperature.