Hi Shatz,
Is is great that you are trying to help your friend. Awesome!!!
When I first started eating keto, I tried to find some substitutes for things I could no longer eat. Specifically, I looked at pasta substitutes. I gave up. Now, instead, I try very hard to focus on all the fantastic foods I can eat, that I can eat guilt free, and I just skip those that I can not. After a while, life just goes on and even if I eat outside of my caloric goals it is still all keto foods.
One alternative to marzipan is just to not bother at all. With addictive behaviors, abstinence and intentionally replacing previous, unhealthy, patterns of eating, with new, “healthy”, patterns of eating, might be a better choice instead feeding the previous addiction. It is my personal view that eating things that are “sweet”, from sugar or sugar substitutes, is not a great choice as it would tend to stimulate the very behaviors I want to abandon.
As I am no Ansel Keys, I would never be so arrogant, bold, deceptive, or self aggrandizing as to tell you or your friend what is best for you or your friend. We must all find our own path and I am only suggesting an alternative approach that has worked well for myself.
Best Regards,
Richard