Preheat your oven to 400 degrees.
Washing your plums & cut in half & remove the pits.
Place on a large baking sheet - insides up.
Roast plums for about 20 minutes.
Remove & carefully transfer them to the food processor.
Allow your oven to cool to about 170-200 degrees.
Process until smooth.
Then transfer to a large bowl & add your sugar.
Mix well so that all the sugar dissolves.
Pour onto another baking sheet lined with parchment - make sure your parchment is larger than your sheet. You want all of the liquid to be contained in the parchment.
Once your oven has cooled to the right temperature - place your baking sheet back in & bake for 6-8 hours.
You know it's done when it's no longer sticky & has a smooth surface.
Store in an airtight container.