1 bag (12 ounces) frozen cranberries
1 jar (12 ounces) red-currant jelly
In a medium saucepan, combine cranberries and jelly. Bring to a boil, reduce heat to a simmer, and cook, stirring occasionally, until cranberries have burst and liquid has reduced to a syrup, 20 to 30 minutes.
Transfer to a serving dish, and let cool.