Melted sugar is extremely hot and can cause serious burns, so unless you have a chef’s brass fingers, avoid testing the glaze against your skin. Using two spoons is a safer bet.
Place the jam, sugar, and water in a heavy-bottomed saucepan. Bring to a boil over medium heat, stirring constantly.
Lower the heat and continue cooking until the mixture can be pulled into a ¼-inch (6-mm) thread between your thumb and index finger or between the back of 2 spoons.
Quickly remove the pan from the heat, strain, and use immediately. Stor