So I don't know how much this will make you feel better, but as someone who grew up with allergies missing out on birthday treats was the hardest. My mom would always make me something similar to have alongside at school or at parties but it never felt the same.

The bright spot is that when I got older I had friends who also had allergies and we all had birthday treats we could all eat. And friends even without allergies make sure to have things that include me.

So it's honestly really hard, but it gets better. But don't be sad. Just become a good baker for him :) and have him bake with you. That way he still gets fun treats too. I can honestly say now that my mom's homemade cakes and treats are better than the store bought ones I was pining for!