Wash the plums, cut them into slices and stone them. Weigh 1 kg of flesh. Caramelise sugar in a large pot until golden brown. Stir in the flaked almonds. Remove the pot from the heat.
Add plums and jam sugar and stir in. Season with cinnamon and lemon juice. Leave to stand for about 3 hours. Bring to the boil while stirring and let it boil effervescently for 4 minutes. Pour hot into glasses and close them immediately