Prepare the apples and plums by slicing and coring them– no need to peel, as you'll be blending the mixture.

Place the fruit and water in the bowl of your slow cooker, then cover and set to cook on on high for 4 hours (or low for 6 hours), until the apples are very soft.

Use an immersion blender to puree the fruit or transfer fruit to a blender and blend slowly. Careful not to overblend, the fruit will become soupy very quickly if you're using a high-speed blender.

Store plum applesauce in the fridge for a week, or freeze for up to 6 months. For baby, use an ice cube tray or small snack baggie to portion out plum applesauce before freezing.