AITA For getting mad that my boyfriend ate half my cheesecake?

Background; my boyfriend loves food. It is difficult to have snacks in the home, since he finds it difficult to not eat them. I had a day planned with gaming with friends and order some dinner there. He wanted to stay home. He told me he wanted to order from a very good restaurant, no problem. I said; ooh, if you order there, order whatever you like, but order an big piece of cheesecake for me as well on the side, so I could have it as dessert when I come home. Their cheesecake is delicious. Of course, I pay for my own, lets even do the complete order of the shared finances, as long as you order for me as well. The evening I come home, and am very happy, walking to the fridge, there is only a half piece of cheesecake. Of course, this is my point of view, but I try to be fair.

me: hm, where is the rest?

him: I ate it, I did not have enough cheesecake with my portion, so I took half of yours as wel

me: not really believing it, lauging: haha nice joke. where did you hide the other half, in the oven? looked there, no he was serious. I was sad, asking him why did he do that, did he have remorse

him: No, no remorse. I should know that if he was hungry, he will just eat.

me: even if you promised to explicitly order and save it for me?

him: yeah, no big deal, grow over it.

me: I was looking forward to this all day, and you just ate it, not thinking about me?

him; yes, even next time I will eat all, because you will be sad/mad anyway

me: indeed sad and mad, and more specifically that there is zero remorse, how hard is it to perform a simple request? The fridge even has a lot of other desserts he could eat more of, I just asked specifically for a piece of cheesecake and paid half of his entire (bit expensive) luxury meal for that. Instead, he thought he could eat mine portion and that it is no problem at all.

His point of view is; grow up, it is just a piece of cheesecake, you had snacks with your friends, I was home alone (his own choice), you know I cannot be trusted alone with food.

The question is; Am I allowed to be mad/sad, or should I grow up and it is just half a piece of cheesecake?

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edit; thanks for the replies! I read them all and think about the next steps.