In a medium-sized saucepan, add cranberries, water, juice, white sugar, and cinnamon stick.
Bring to a boil, stirring.
Allow to boil for 3-4 minutes to soften the cranberries.
Using a slotted spoon, remove the cranberries and set aside.
Reduce heat and simmer the remaining liquid until reduced by half.
Remove from heat.
Remove the cinnamon stick and discard.
Add cranberries back to the pot.
Add Grand Marnier if using.
Blend the mixture with a hand blender on low until smooth.
Stir in the brown sugar and Dijon, mixing until well combined.
Pour into a bowl and cover.
Refrigerate for minimum 2 hours or until completely cooled before serving.
If the sauce is too thick, add a tbsp or water or cranberry juice to thin it out.