Dulce de leche (pronounced DOOL-se de LE-che, meaning candy of milk or milk jelly in Spanish) is a rich and decadent sauce or syrup, similar in flavor to caramel.Unlike caramel, however, which is made by heating sugar, dulce de leche is prepared by heating sweetened condensed milk.Dulce de leche is especially common in the desserts of various South American countries, including Argentina and Uruguay. The can may burst. 2  Even though this is a popular way to make dulce de leche, it is unsafe and not recommended. 3  Do not overcook the dulce de leche, especially if you use the saucepan method, because it will burn easily.