This recipe is used in our Passion Fruit and Lime Cake.
Combine sugar, passion fruit puree, and egg yolks in a medium saucepan and place over medium heat. Cook, whisking constantly, until thick enough to coat the back of a spoon, 12 to 15 minutes. Remove from heat; stir in the butter, piece by piece, until melted. Cool and cover with plastic wrap. Refrigerate until needed, or up to 3 days. Curds freeze well for up to 1 month.