Cut the pineapples:

• Wash the pineapples. Cut away the skin and eye spots. Slice in half. If using a blender, cut away the tough, fibrous core and slice the fruit into smaller chunks.
• Grate each pineapple until you reach the tough, fibrous core. Discard the core. (Note: It's a good ideal to wear hand gloves if grating by hand. due to the acidity of the juices). If using a blender, blitz pineapple chunks until mushy, about 10 seconds.
• Pour the grated pineapples with juices into a large pan. Heat up over medium heat.
• When the juices come to a boil, stir in the cinnamon bark, cloves and star anise segments. Let simmer for 2 to 2.5 hours, stirring occasionally around the edges and the bottom.
• When the mixture has reduced by half, stir in ⅔ of the rock sugar. Once dissolved, taste the jam, and add more sugar as desired. You don't want the jam to be too tart, it should be pleasantly sweet and tangy.
• As the mixture gets drier and thicker, reduce the heat. Stir frequently to prevent burning. Add salt and vanilla extract (optional) last.
• Reduce until the jam is very thick and dry to the point where you can't see any liquids or syrup at the bottom of the pan. You should also start to see lots of pineapple 'hairs', i.e. the fibers sticking out. The key is to get the pineapple jam dry enough, but still moist to the touch.
• Dish out into a bowl and let cool completely to room temperature. Remove the spices, cover with clingwrap and chill. Or, store in sealed glass jars and refrigerate. The jam will keep in the chiller, if handled well, for up to 3 weeks.