I think one of the biggest challenges is finding a super kid friendly dish...it is her party after all...and something that adults will like, too. I've done pizza because the toppings can be different. I bet you can find a way to make it "fairy-like". My favorite kid-pleaser crock pot recipe is an awesome mac and cheese. Like another post, you could use any shape pasta, so bowties as "fairy wings" would work great. This recipe is really cheesy and has hidden veggies.
Someone else already asked for the recipe, so I'll type it in below. It is modified from the original to use less butter and cheese and add sneaky veggies. I've had many, many compliments on it, even from people who have eaten the original version.
Crock Pot Mac and Cheese
2 boxes of Ronzoni Smart Taste (high calcium, high fiber) elbow macaroni, or whatever you like
1/2 c (1 stick) margarine or butter, melted
Cook according to package, drain, put in slow cooker. Add margarine.
3 eggs, beaten
2 (12-oz can) evaporated skim milk
5 c (20 oz) shredded cheddar cheese, divided
2 (10 3/4-oz) can condensed cheddar cheese soup
1 c butternut squash, puree (frozen box of butternut squash...nuke 4 min...already pureed...scoop out 1 c)
2 c skim milk
1 c chick peas, pureed
1/4 t paprika
In a bowl, combine eggs, evap. milk, soup, squash and 4 c cheese. In blender, combine chick peas and milk and make into puree. Add to bowl. Pour all that over mac in crock pot and stir to combine. Cover and cook on low for 4 hours. Sprinkle with remaining 1 c cheese. Cook 15 min longer. Sprinkle with paprika. Serves many, many, many happy children (and adults).
HALF this recipe if you have a smaller crock pot…as written, it barely fits in a big one. Leftovers freeze well.