In a large mixing bowl, combine the milk, brewed coffee, almond or vanilla extract, and maple syrup. Whisk the mixture thoroughly until smooth and well-combined.
Pour the mixture into an empty Ninja Creami pint container, place the lid on the container, and place into the freezer, on a level surface, and freeze for 24 hours.
Remove the pint container from the freezer and remove the lid. Add the pint to the bowl of the Ninja Creami and secure the lid. Insert the bowl into the machine, locking it into place. Select the Ice Cream function. Once the ice cream has been spun, remove it from the machine.
If you would like mix ins, use a long wooden spoon to create a well in the ice cream that is about 1.5 inches wide and reaches the bottom of the pint. Add chocolate chips or cholate bites to this well.
Reinsert the bowl into the machine and use Mix In function. Once finished, remove from the machine and serve.