Served with scones, plain old toast, or over ice cream, this tart curd is simply wonderful!
Combine yolks, cranberries, orange juice, and sugar in a small saucepan. Whisk to combine. Set over medium heat, and stir constantly with a wooden spoon, making sure to stir sides and bottom of pan. Cook until mixture is thick enough to coat back of wooden spoon, 5 to 7 minutes.
Remove saucepan from heat. Add butter, one piece at a time, stirring with the wooden spoon until consistency is smooth.
Transfer mixture to a medium bowl. Lay a sheet of plastic wrap directly on the surface of the curd to avoid a skin from forming; wrap tightly. Let cool; refrigerate until firm and chilled, at least 1 hour.