Hi there! Thanks for visiting us here at the Disney Parks Moms Panel. Your question is a great one and one a lot of other Guests have as well.
Dinner at Chef Mickey's is a lot of fun, you guys will have a great time. When you leave there, you most certainly can continue your day at Magic Kingdom. If you have a standard base ticket, you are allowed reentry into the
same park multiple times a day. If you have a Park Hopper ticket, you are allowed into all four theme parks, multiple times, each day.
I hope this helps plan your day! If you have any other questions, I'd love for you to come back and
ask me. Your vacation will be here before you know it, have a great time!