Here are my personal favorites at each of the different parks...
MK
- Dole Whip Floats
- Ice cream sandwich cookie from the ice cream parlor on main street (you can pick the ice cream flavor)
- Popcorn
- LeFou's Brew at Gaston's Tavern (more of a beverage but still a must)
- Auntie Gravity's soft serve ice cream in Tomorrowland
Epcot
- Popcorn
- Cloud berry horn at the Norway Pavilion
- Karamel Keutch in Germany Pavilion (love everything in there but really love the caramel popcorn)
- Frozen Cokes at Club Cool
- Kaki Gori (shaved ice) in Japan Pavilion
- Different chocolate bars from around the World Showcase
DHS
- Carrot Cake Cookie
- Popcorn
- Frozen Lemonade from the Fresh Produce Market down Hollywood BLVD
- Chocolate/peanut butter cupcake from Starring Rolls
AK
- Soft serve ice cream from the Anandapur ice cream truck next to Expedition Everest (love this place!!!)
DTD
- Goofy's Candy Co....the slushes (so many to choose from and you can sample the different flavors), chocolate covered strawberries and just about anything else in there

- Ghiradelli Ice Cream Shop
Resorts
- Beaches and Cream Soda Shop at the Beach Club Resort....most favorite thing there is the No Way Jose Ice Cream Sundae.