I also made a batch of these yesterday, together with the jelly mooncake with chocolate filling. The jelly skin's recipe is the same as before, but instead of chocolate filling, I made a custard jelly--which was yellow--as the filling, so as to recreate the "egg" look. Bwahaha.
The recipe for the custard filling is real easy:
1. In a pot, combine 1 cup of water, 90g sugar, 2 ts agar agar and 125ml milk. Separately, combine half a tb of custard powder and 2 tb water. Mix the powder and water till a smooth yellow liquid is formed, then pour this into the pot as well.
2. Heat the pot to come to a slow boil.
3. Turn off heat and fill mini plastic cups with the mixture. The important thing is that the size of these cups must be able to fit into your mooncake moulds, as the custard filling will be inside the jelly mooncake.
4. After solidifying (10 minutes), use a knife to remove the custard jellies from the cups. Then, follow the recipe for the jelly mooncakes with chocolate filling, but instead of the chocolate filling, use the custard jellies instead!