In a medium saucepan, combine the blueberries, apple juice, and cinnamon.
Heat over medium heat for about 5 minutes, or until the berries soften and begin to break down.
While the blueberries are heating, whisk together the orange juice concentrate and arrowroot powder (or cornstarch) in a small bowl until no lumps remain.
Pour the orange juice mixture into the hot blueberry mixture in the saucepan, stirring constantly.
Bring the sauce to a boil.
Once boiling, reduce the heat to low and simmer for 2 to 3 minutes, stirring, until the sauce has thickened.
Remove from heat and stir in the optional maple syrup to taste.
Serve warm or let it cool completely.
Adjust the thickness to your liking. Use 2 tablespoons (30 ml / 1 fl oz) of starch for a pourable sauce, or 3 tablespoons (45 ml / 1.5 fl oz) for a thicker, spoonable consistency once cooled.
Add a teaspoon of fresh orange zest with the cinnamon for an extra pop of bright citrus flavor.