Place the chopped pumpkin or squash into a large preserving pan. Add water, grated ginger and spices and bring to the boil.
Turn down the heat to a gentle simmer until the pumpkin is tender - about 30 to 40 minutes.
Remove the cinnamon stick from the pan and use a stick blender to puree the cooked pumpkin until smooth.
Keep the pureed pumpkin on a low heat, add the jam sugar and stir until the sugar has dissolved. Add the lemon juice and bring to a rolling boil.
Boil for about 5 to 8 minutes until you have reached setting point. Setting point is reached when the jam thermometer reaches 104℃ or 220F.
Alternatively, use the wrinkle test: Remove your pan from the heat and test for setting point by dropping a little jam onto a cold saucer, return to the fridge and leave to cool for a minute. Push the jam gently with your fingertip, if the jam crinkles, setting point has been reached. If not, reboil for a couple of minutes and repeat until setting point is reached.
Seal the jars as quickly as possible and store in a cool dark place and use within 12 months.