The boy wants to make vegan sponge cake.

Here's where I plan to start my investigations. Looks like we're going to have to experiment with a commercial egg replacer, but luckily I know where to get some.

I've always been happy with the denser types of cake (carrot cakes and fruit cakes) that I usually bake. We have our few recipes that work well and I don't often go looking for new ones. But the boy has now had the chance to become re-acquanted with his mother's baking, and he wants to do similar things at home; fluffy sponge cakes inspire the most urgency, but he wants to make them so I can eat them too, bless him.

Angel food cake: never heard of it, but I assume it's the US name for sponge cake. Good good, another search term to use.