1Place the blueberries in a deep baking pan and cover them evenly with the sugar.Mush them gently, just to get some of the berries juice out. Leave it overnight. The blueberries juice will turn the sugar into syrup.
2Preheat the oven to 150F.
3Add to the berry mix the juice of the freshly squeezed lemon.
4Bake it for 2 .5 hours. Let it cool. Bake it for another hour to hour and a half, or until the syrup thicken. Taste it by dripping some of the syrup in a glass with water. If the drop gets to the bottom on the glass without diluting, the jam it is ready.