There are many versions of this recipe, and this one is one of the easiest for making NYC's famous Egg Cream. It’s a bit baffling why this classic drink was given such a name, since it contains neither eggs nor cream. It’s written that the drink was created in New York City in the late 19th century as a variation of classic milkshakes that were so popular at neighborhood soda fountains. When made correctly, it should display three layers with dark brown on the bottom, a lighter chocolate brown in the center, and a cream-colored foamy layer on top.
Squeeze or pour about 2 inches worth of chocolate syrup into a tall 20-ounce glass (such as a Pilsener glass).
Pour in the milk; DO NOT STIR.
Hold an inverted soup spoon over the glass. Slowly pour seltzer onto the back of the spoon, letting it cascade into the glass, until the glass is about 3/4 full. Remove the spoon, then add enough seltzer to fill the glass, creating a foamy layer on top.
Drizzle a few thin lines of chocolate syrup on top of the foamy layer. Insert a straw; serve immediately.