In a saucepan, combine granulated sugar, brown sugar, orange juice, water, cinnamon stick, and salt. Bring to a boil over medium-high heat, stirring until the sugar fully dissolves, then keep the boil steady for about 30 seconds as the mixture looks clear.

Add fresh cranberries to the boiling mixture and return to a boil. Once bubbling again, keep it at a boil for 1 minute so the berries start bursting at the edges.

Reduce heat to low and simmer, stirring often, for 10-12 minutes. Continue until most berries burst and the sauce thickens enough to coat the back of a spoon.

Remove from heat and stir in orange zest and vanilla extract, then discard the cinnamon stick. The sauce should turn darker red and look glossy right away.

Cool to room temperature, then chill until thickened further. Refrigerate for about 5 minutes so it sets to a spoonable, dense texture.