Start by cutting the pumpkin flesh into rough pieces and place them in a large pot. Add the apple juice and lemon juice, then toss in the cinnamon stick and cloves.
Bring everything to a boil and simmer the pumpkin until it's soft. This should take about 10 to 15 minutes, depending on the variety.
Once the pumpkin is soft, remove the pot from the heat and take out the cinnamon stick and cloves. Use an immersion blender to puree the pumpkin until smooth.
Return the pot to the stove and add lemon juice, nutmeg and a pinch of salt. Let the mixture cook, stirring frequently, for about 15-20 minutes until it thickens to your desired consistency.
Fill the hot pumpkin jam into clean jars while it's still hot and seal them tightly. As the jars cool, a vacuum seal will form, helping your pumpkin jam last longer.