Lemon Desert

from the 15th century Portuguese cookbook:

Lemon dessert

Separate (select) a few lemons with very thick peels, pierce each end and cook them in water with a little ash. To know if they're cooked, pierce them with a needle. Place the lemons in cold water, cleaning them quickly/lightly inside, without opening them completely, and agitating them afterwards in another clean water. Leave the lemons during three days to infuse, changing the water three times a day. Each day give them a boil, returning them always to the cold water. At the end of those three days finish cleaning the lemons, and take them to the fire to cook very well to the end of not letting them get too hard. Finally make a syrup and pour it boiling over the lemons, in sufficient quantity to cover them. Leave the fruit in that syrup for fifteen days and each day give just the syrup a boil. If it is becoming too thick, before the fifteen days, bring it to a boil with the lemons and add a little flower water.