Mix 350ml fat free fairlife, 35ml key lime juice, ½ tsp vanilla, 50g artificial sweetener, ⅛ tsp salt, ¼ tsp xanthan gum, and lime zest.
Blend the mixture.
Pour into a container and freeze overnight.
Place the frozen mixture in the Ninja Creami machine on light ice cream mode and spin once.
If powdery, go around the edges with a knife and respin on the same mode.
Add 15g graham crackers (reserving some for the top) and spin on the mix-in mode once.
Top with reserved graham crackers and lime zest.
