I can tell you! hehe The one with Neocate you need : 6 scoops Nutramigen (sorry not 3!), 1tbsp corn flour and 180ml cold water.
Mix the cornflour with a little water to form a smooth paste and then gradually add the remaining water. Cook for 3 minutes, stirring continuously until the mixture thickens (probably took a bit longer than 3 min). Take the saucepan off the heat and gradually add the powder, whisking well to form a smooth texture. Leave to cool in a cold water bath -fill a large bowl with cold water and sit the bowl containing the yoghurt in it. Store the yoghurt in a covered container in the fridge.
With oatmilk or any other milk -ricemilk, coconutmilk): https://www.skrewtips.com/2009/04/20/making-yogurt/
Looks super easy but I haven't tried yet. Someone on another forum recommended it. I've ordered some yoghurt culture so will try it when it arrives. I will make it with the oatmilk that is enriched. Its got more calcium than Nutramigen!
Also, a friend told me a trick. If you don't want to buy a thermometer she said to make sure that you can leave your finger in the heated milk for 10 seconds to make sure it is not too hot!
Potatoe puree is easy: boil the poatoes and then put in the food processor with milk!
Spinach puree I haven't done in years was just thinking the other day so maybe google but pretty much the same concept!
Hope this helps a bit!