Sponge fingers were the main treat for all ages. in my childhood. It accompanied coffee and tea for adults, milk and cocoa for children.
It is a flour-egg-water based baked goodie with the addition to the dough of vanilla extract, lemon juice (resembles the italian 'savoiardi' biscuits). The result - finger shaped cookies, spongy inside, crispy outside, coated with sugar.
We had a relative and neighbor (aunt Elki) that was famous in our little town for her 'swollen', delicious, sponge fingers. It was believed she used a certain ingredient which she refused to disclose. The sponge fingers were her 'specialty', her pride. She kept the secret to herself, probably took it with her to the grave, as her daughter and daughter- in- law who lived in other towns, were unaware of her fame and didn't know what it was all about.
My mom made some attempts to find out the secret by adding, and/ or eliminating ingredients. No many options in those days, but the 'usual suspects' were there: soda water, baking powder, baking soda, yeast. Nothing conclusive, as far as I could remember).
(Come to think of it, maybe it was potato starch. Perhaps, it wasn't an ingredient that did the job, but the method, the quantities).
Anyway, I didn't mind the secret as long as I got my treat, and I got it often, There were times when her husband was mostly on the road (sales agent), and she wanted me to sleep at their house. Well, no child likes to leave his bed , but she was also a close relative and I didn't want to upset my mother. So, the sponge fingers and sometimes little gifts, sweetened my bitterness.