Add bueberries to Ninja Creami pint. Mash lightly with a fork. Add sugar and let sit for 5-10 minutes.
Mash again with a fork. Add milk and then Greek yogurt. Stir until combined.
Smooth the top so that it is level. Put on the lid. Place in the freezer on a level surface. Freeze for at least 24 hours.
Remove from the freezer and run water along the outside of the container to allow the outside to unfreeze.
Process on the LITE ICE CREAM setting. If crumbly after processing, add a splash of milk (1 Tbsp) and respin.
Notes
Make sure your blueberries are mostly smashed and mixed in with the other ingredients before freezing. You don't want any air pockets before freezing.
I highly recommend running a little warm water around the edge of your Ninja Creami container before processing. This will help everything get incorporated because it will melt the outside layer of ice cream better.
If you have leftovers, smooth out the top and place back in the freezer. You may need to reprocess (I usually do) before enjoying again.