Preheat the pizzelle iron for 15 minutes. Melt butter and allow to cool.
Beat eggs and sugar together until light and lemon-colored. Add vanilla and lemon zest, if desired. With mixer running, slowly add in butter until incorporated.
In a separate bowl, combine flour, baking powder and salt. Add dry ingredients to wet ingredients a bit at a time and mix until smooth.
Before cooking the first set of pizzelle, spray the iron with non-stick spray. You only need to do this for the first pizzelle of the day.
Add a heaping tablespoon of batter just behind the center of the pizzelle iron. Bake until golden, this can be anywhere from 30 seconds to 2 minutes, depending on your iron . You'll need to experiment to find what works for yours; for my CucinaPro Stainless Steel model this was approximately 1 minute and 40 seconds.
Using a non-stick spatula, immediately remove to a wire rack and allow to cool, or while still warm, shape to make waffle cones, bowls, mock cannoli or trubochki.
Once cooled, carefully clean up the edges and dust with powdered sugar.
Store in an airtight container in layers separated by wax or parchment paper. Makes approximately 2 dozen pizzelle.