Cream the butter. In the container of a stand mixer, or a regular container, beat the butter until it becomes fluffy and pale.
Add the sifted powdered sugar to the butter and continue beating until the sugar disappears and it is well incorporated into the butter. Add the orange zest (if using) and keep running the mixer again for 30 seconds.
Add the eggs one by one. Beat the mixture after the addition of each egg until it disappears completely in the cookie batter.
Add the sifted flour to the batter, and with a spatula fold it carefully into the batter. Don't use the mixer at this point. Incorporating the flour manually into the batter yields a better cookie texture.
In a small bowl, mix the warm milk and Ammonia with a spoon, when the mixture becomes frothy, fold it into the batter until it is well incorporated. A soft unstick batter should come together at this point.
Transfer 1 cup of the batter at a time to a pastry bag fitted with a flat cookie tip. Pipe cookies that are 3-4 inches long.
Bake the cookies in a preheated 170 C or 350 F oven for 12 minutes.
Transfer the cookies to a metal rack and let the cookies cool completely to room temperature.
Store the cookies in airtight containers.
Serve with tea and coffee