Whisk or froth the milk, protein powder, pudding mix, sweetener, vanilla, and salt directly in the Ninja Creami pint container until completely emulsified and no dry clumps remain.
Secure the lid and place the pint on a level surface in the freezer for exactly 24 hours.
Remove the pint from the freezer and scrape any frozen peak or 'hump' from the center using a spoon to ensure a level surface for the blade.
Place the pint into the outer bowl, lock the lid with the Creami paddle, and install it into the machine.
Select the 'Lite Ice Cream' program and allow the cycle to finish.
If the texture appears crumbly or powdery after the first spin, add 1 tablespoon of milk to the center and run the 'Re-spin' program.
For mix-ins, create a 1-inch wide hole down to the bottom of the pint, add toppings, and run the 'Mix-in' program.
Serve immediately for a soft-serve consistency or freeze for 15 minutes for a firmer scoop.