In a stove top pan melt butter, set aside and cool.
Using a stand mixer with the paddle attachment or hand mixer, add eggs and sugar. Beat until light and creamy.
Add melted butter and beat until combined.
Pour in vanilla extract and beat.
In a bowl, add flour, baking soda and cocoa. Mix together until combined. Add to the mixing bowl a little at a time and beat until the batter is smooth. Batter will be sticky.
Optional: Add 1/2-1 cup of finely ground pecans and mix.
Heat the pizzelle iron. Using a cookie scoop or teaspoon, drop batter into the middle of each circle on the iron. You may need to experiment with how much batter to drop, depending on the size of the iron. If pizzelles stick, brush with a little vegetable oil. Close the pizzelle iron and bake for about 45 seconds. You want the cookie to be lightly browned. If your iron has a setting, move to setting 3 or 4 (for a little crunchier pizzelle). You can also tell when the pizzelles are done because the steam will stop coming out of the iron.
Once done, remove pizzelles to a baking sheet. Let sit for a few minutes. Flip and continue too cool.
Sprinkle with powdered sugar. Serve and enjoy!
Store in an air tight tin lined with foil. To freeze; stack and wrapped in heavy duty foil, place in a freezer bag for up to 3 months.