In a small mixing bowl, combine sliced strawberries and sweetener. Let them sit for 15 minutes until the strawberries start to release their juices.
Add the Greek yogurt and milk to the bowl. Use an immersion blender to blend until combined, but be careful not to overmix.
Pour the mixture into the Ninja Creami pint container, making sure not to go over the max fill line.
Place the container on a level surface in the freezer and let it freeze for 24 hours or until solid.
Once frozen, remove the container from the freezer and run it under hot water for 30 seconds to loosen the sides.
Place the container in the outer bowl of the Ninja Creami, lock the lid into place, and insert it into the Ninja Creami ice cream maker. Press the Lite Ice Cream button and allow the cycle to complete.
After the first spin, check the consistency of the frozen yogurt. If it looks powdery, return to the machine and press the Re-spin button.
Scoop the frozen yogurt into bowls, top with fresh fruit and enjoy immediately!