Add cranberries, orange zest, orange juice, sugar, cinnamon, and jalapeño (if using) to a medium saucepan.

Add enough water to just barely cover the cranberries.

Bring to a boil over medium-high heat, then reduce heat to a simmer.

Cook for 15–20 minutes, stirring occasionally, until the cranberries burst and the sauce thickens.

Remove from heat and let cool completely. The sauce will thicken more as it cools.