Place a plate in the freezer to the jam consistency.
Combine the raspberries, sugar and lemon juice in a pan.
Mix everything well and let it cook on a medium flame.
Lightly mash the berries using a spoon or spatula.
Let it cook for 10 minutes or until it thickens.
To test the doneness, turn off the heat place a small spoon of jam on the chilled plate. Draw your finger through the jam. If it stays apart, it is done.
Once it is done, add the chopped dark chocolate to the berry mixture and mix it well.
No need to turn on the heat.
Let it cool down and store in the refrigerator for up to a week or two.
Video
Notes
The jam will thicken more as it cools. Always turn off the heat to test the consistency. It will prevent the jam from over-cooking.