I make my own custard using his dairy free formula
heres a recipe
120ml prepared formula
1 egg yolk (make sure there is no egg white or it will turn to scrambled egg)
2 tsp cornflour/cornstarch
a few drops of vanilla
1/2 tsp of sugar or leave the sugar out and mix the cooked custard with pureed fruit
instructions put 2 tsp of cornstarch into a microwave jug, whisk with a fork as you mix the prepared formula in, mix the egg yolk, vanilla essence and sugar in. Microwave for around 40 seconds, stir and then another 10 secs stir and repeat until thick.
I also give mashed banana for puddings and this custard mainly. You can vary the custard by changing the essences if you are comfortable doing that. I have used banana and strawberry essence before and you can also add 1/2 t cocoa powder for chocolate custard.