Food Allergies Treatment

My 11mo old son recently has been diagnosed with a severe milk allergy, and I am at my wits end. I am scared with everything he comes in contact with and I don’t know what to do. My question is can I feed him food from an Organic food store? Also, are there any recepies out there of cakes. His birthday is on the 22nd and I would love for him to have a cake to put his hands in.
Thanks,
Katrina
(Elijah’s Mom)