Overseas Adventure Travel Welcome Dinner at Parilla El Mirasol. Flan with dulce de leche. Dulce de leche classic traditional Argentine sweet Traditionally, it is made by heating sweetened cow's milk until it caramelizes and achieves a thick consistency, enough to act as a spread, a filling for cakes and pies, or an ice cream topping.Today, dulce de leche is sometimes flavored with vanilla, lemon, or cinnamon, and is used to flavor candies, cakes, cookies, waffles, and ice creams.