01 - Rinse cranberries thoroughly and discard any soft or spoiled berries.
02 - In a medium saucepan, mix cranberries, orange zest, orange juice, sugar, and water.
03 - Bring the mixture to a boil over medium-high heat, stirring occasionally.
04 - Lower heat to medium-low and simmer for 10 to 12 minutes, stirring occasionally, until cranberries burst and sauce thickens.
05 - Stir in ground cinnamon and allspice, if using.
06 - Remove from heat and allow to cool to room temperature; sauce will thicken further.
07 - Transfer to a serving container or airtight jar and refrigerate until serving.