Carlota,
Thanks for asking your question to planDisney!
What a wonderful way to help your little guy celebrate! The great news is that Mickey Mouse Celebration Cakes have recently returned to select Walt Disney World restaurants, including
Chef Mickey's!
Because you have already made your dining reservation, you will want to ask the front desk when you check in if they have any cakes available. There is no way right now to add that request to your current reservation, unfortunately. At this time, they can only be requested when the initial reservation is made. When you ask, know that they are subject to availability, so I would leave that as a surprise, just in case they have run out.
Technically you could cancel your current reservation, and then make a new reservation and request the cake at that time. However, Chef Mickey's appears to be booked up that whole week for dinner, so I am guessing you could lose your original reservation, and not get a new one, if you tried that.
I would not take that chance!BONUS TIPSo what should you do if you get to the restaurant, and they indicate that they are all out of Celebration Cakes? One thing you could do is to run out quickly to the
Contempo Café, the food court restaurant that is right there next to Chef Mickey's entrance. They often will have the same cakes in stock, or some other sweet options that could serve as your celebration treat!
Have a Magical Vacation!
Doug