I am allergic to cow's milk. I have made a quiche with goat cheeses and soy milk without a problem. If cooking with nutmeg and other spices (as my recipe does) any nutty flavor of the soy is covered and even those who can have milk and do not like milk have told me the taste is virtually indistinguishable.

Be careful using Lactaid milk for a person that is lactose intollerant, as I am lactose intollerant and cannot use that lactaid milk, it affects me that same as regular milk. There are different severities of lactose intollerance. I can eat cheese of any kind, but will keel over in pain, with milk. I cannot eat yogurt, but I can eat butter, go figure, as I say everybody is different. I use rice milk in any recipie that calls for regular milk and have no problem with the recipie.
Good luck.

I'm using goat cheese, which is fine, but I don't want to mess with goat milk. I don't know why, but I didn't even think of lactaid!

Doesn't the recipe call for cheese also? They have lactose also.

Oatmilk tends to be a better substitute than soy, and not as heavily processed.

Why don't you use lactaid milk instead? use the 100% lactose-free and they should be fine. I'm lactose intolerant and I drink lactaid and I'd think it would be safer to try a quiche with this instead of soy milk, since they're not allergic to dairy in general.

I'm making a quiche for someone who is lactose intolerant. I've seen recipes for using soy milk but wanted to know if anyone has done it themselves. If so, does it still turn out fluffy? Does it cook "up" as well as with milk, or is it a little flatter? Thanks!