Combine ingredients (except for the milk and graham crackers) in a blender and blend until smooth
Pour mixture into Ninja CREAMi container
Put in the freezer for at least 24 hours
Remove container from the freezer and leave on the counter for 10 minutes
If there's a little "hump" on top of the mixture, scrape it off with a spoon or butter knife until the top is smooth.
Place in the Ninja CREAMi machine and spin on the "ice cream" setting.
Remove lid and check the consistency of the ice cream, if it's still powdery, you can add 1-2 tablespoons of milk and spin on the "ice cream" setting again. Continue to go through spinning cycles until the ice cream is nice and smooth. Meanwhile, crush up graham crackers into small chunks.
Create a hole in the center of the ice cream and pour in half of the graham crackers and spin one final time on the "mix in" setting.
Scoop out ice cream and serve with the remaining graham cracker crumbs.