Melt the butter and set aside to cool.
In a medium mixing bowl whisk together the flour, cocoa, salt and baking powder.
In a large mixing bowl vigorously whisk together the eggs and sugar until blended. Add the vanilla and melted butter and whisk until combined.
Sift the dry ingredients into the butter and egg mixture and fold together with a spatula. This batter will be thick.
Heat your pizzelle iron until a drop of water sizzles on the cooking surface. Lightly coat the hot iron with nonstick cooking spray. Scoop the batter into a pipping bag fit with a large tip (or cut the corner from a ziplock bag) I used a large Wilton 2A tip.
Pipe about 1 tablespoon 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 the next time. It will take a few tries to get them just right.
Remove the hot pizzelles to a wire rack to cool.