Preheat the slow cooker if necessary; see the manufacturer's instructions. Coarsely grate the beetroot and put it into the slow cooker pot with all the remaining ingredients.
Mix everything together thoroughly, then cover with the lid and cook on high for 6–7 hours, stirring once or twice, until the beetroot is tender and the plums pulpy.
Warm 4 clean jars in a low oven for 5 minutes. Ladle the hot chutney into the warm jars, cover the surface with waxed discs and screw the lids in place. Label and store in a cool place until required. Once opened, store in the refrigerator.
Serve with cheese, cold sliced ham or with the Courgette & Broad Bean Frittata (see