Rinse the fresh cranberries thoroughly under cool running water, removing any damaged berries. Transfer the rinsed cranberries into your crockpot.
Add the granulated sugar, freshly squeezed orange juice, water, and kosher salt. Stir everything together until combined.
Cover the crockpot with the lid and cook on HIGH for approximately 3½ hours, stirring occasionally, about once every hour.
After approximately 3½ hours, remove the lid and stir the cranberries. Many should have softened and started bursting open.
Using a wooden spoon, gently press some of the cranberries against the side of the crockpot to burst them. Press more cranberries for a smoother sauce or leave more whole for a chunkier consistency.
Add the ground cinnamon, Clementine zest, and a small splash of Grand Marnier. Stir well and taste. Add a little more Grand Marnier if desired.
Replace the lid and continue cooking on HIGH for another 30 to 45 minutes.
Once finished, carefully ladle the cranberry sauce into a shallow, heat-safe storage container. Allow it to cool on the counter for approximately 30 to 40 minutes, then cover and refrigerate promptly.
Refrigerate for several hours or overnight. The cranberry sauce will continue thickening as it cools and chills.
Serve chilled or gently reheat before serving. Enjoy!