It’s a snack from Henan!
Henan’s authentic egg-filled pancakes are 15 cm in diameter pancakes with a layer of bean paste spread on top and cut into strips.
Tianjin’s improved egg-filled pancakes are about 10 centimeters in diameter, which is thinner and smaller than those in Henan. The method is pretty much the same. After it's done, put a layer of sauce on top that I can't tell what it is, and some pickles. Sometimes ham can also be added. The ones from Henan only add sauce.
In comparison, I prefer Tianjin’s improved version of egg-filled pancakes, because when each pancake contains an egg, Tianjin’s pancakes have a higher proportion of eggs and are more delicious. And pickles are added to relieve the greasiness, because the stuffed pancakes are very greasy.
I am from Luoyang and went to school in Tianjin. So compare the cakes from these two places. You are from Beijing. I guess Tianjin’s improved egg-filled cakes should be similar to your Beijing ones.
Also, let me tell you a super delicious way to make stuffed cakes. Buy two stuffed cakes, and then buy a skewer of tenderloin from the stall selling sesame seed loin next to it. Sandwich it between the two stuffed cakes and eat it. It feels so good to wake up!
My answer is a bit off topic, but most people can’t tell who invented it, but it must have originated in Henan! These snacks all originated from the folk and have no specific originator.
Thank you