Hi Miranda,
Thank you so much for visiting the Disney Parks Moms Panel with your question. Dinner at
Chef Mickey's is so much fun! Meeting Disney characters dressed up in their chef gear is really a good time. I also love the setting of this restaurant at Disney's Contemporary Resort, and especially hearing the monorail whoosh by as it heads through the tower.
I think that the timeline to have dinner at Chef Mickey's at 7:55 p.m. and then be back and ready to see
Wishes Nighttime Spectacular in Magic Kingdom at 10:00 p.m. is just too tight. Your dinner will include having a photo taken, and I am sure that you will want to see each of the characters and eat at a leisurely pace. By the time you do this, my guess is that you would be ready to leave Disney's Contemporary Resort around 9:00 p.m. at the earliest, but more likely 9:30 p.m. The good news is that it is only about a five to ten minute walk to get to Magic Kingdom from Disney's Contemporary Resort, which will almost always be faster than taking the monorail. Even so, by the time you get to the Magic Kingdom, through the bag check and into the park, and into a place to see the fireworks, I think that you will just be too pressed for time. Also, by the time you get to Magic Kingdom, most other guests will have found places to watch the fireworks, making getting up Main Street U.S.A. and finding a good spot difficult.
I suggest that if you can, move your Chef Mickey's reservation back about an hour - I would start it at 7:000 p.m. at the latest. Alternately, you could chose another night to see Wishes Nighttime Spectacular.
I hope that these thoughts are helpful for you, Miranda! Please do not hesitate to ask if you have any further questions.