Blend the cottage cheese until smooth using a hand blender or high powered blender.
Next, blend in the high protein milk, protein powder, and stevia (if using). If you're planning to make chocolate ice cream, this is where you should add in cocoa powder, nut butter, or any other ingredients you want incorporated fully into the ice cream mixture (not add-ins like cookies or chocolate).
Blend until smooth, then pour the mixture into the Ninja Creami container and smooth out the surface of the mixture until smooth. Add the lid, then freeze for about 24 hours until frozen solid, making sure the container is on a flat surface.
Once the mixture is completely frozen, add it to the Ninja Creami according to the manufacturer's instructions provided with the machine.
Process on the "Lite Ice Cream" setting, according to the directions provided with the machine.
If the mixture after processing appears powdery instead of smooth and creamy, simply add a teaspoon or two of milk, and process on the "re-spin" setting, according to the manufacturer's instructions.
Serve with your favourite toppings, or add mix-ins and process on the "mix-in" setting according to the manufacturer's instructions.