Lightbrite…………….
Those of us older than 60 remember when egg creams were a staple of the corner stationery/candy store.
Contrary to your understanding egg creams could be made with chocolate or VANILLA syrup.
Growing up, the seltzer man delivered a case of siphon bottles to our home every week. My father and eldest brother loved chocolate egg creams, my mother preferred Vanilla.
As for me, I preferred the pretzel Rod that was the usual accompiament.