To a medium pot, add the cranberries, sugar, and juice from ½ an orange. Cook over medium-low heat, stirring occasionally, until cranberries soften and start popping (you'll hear them!)
Add cranberry mixture to a blender with milk and pudding mix. Blend until combined. Add heavy cream and blend for 5 seconds to mix.
Pour mixture into Ninja Creami container. Place lid on container and freeze on a level surface in the freezer for at least 24 hours.
Remove from the freezer. Run hot water on the outside of the container for 30 seconds to thaw the outer layer.
Process on the ice cream setting. If crumbly or too hard, add a small splash of milk and respin.
Notes
I prefer to run hot water on the ouside of the Ninja Creami before processing to thaw the outer layer, but if you like, you can leave the container out for 15 minutes before processing to thaw.
If you have leftovers, smooth out the top of the ice cream to make level again and return to the freezer. You may need to reprocess before enjoying again.