Spend a week in Portugal and no doubt you’ll end up with a serious addiction to pasteis de natas. Sweet and creamy yet with a slight crunch, these small custard tarts line the windows of most bakeries and coffee shops. The locals blanket them with cinnamon and a smidgen of powdered sugar before consuming them at breakfast or as a snack. In my case no day in Portugal was complete without at least one of these bite-sized treats. Although I found them throughout Portugal, legend has it that de natas originated on the outskirts of Lisbon, at Belem’s Mosteiro dos Jerónimos. There lay bakers produced pasteis de natas for the general public. In the early 19th century, when the monastery closed, a neighboring confectioner, Domingo Rafael Alves, bought the recipe from one of the out-of-work bakers and started offering them in his shop. Today Alves’ Pasteis de Belem has become a tourist attraction in its own right. Made using the monastery’s original, secret recipe, Pasteis de Belem’s tarts draw countless customers to the cafe seven …