Start by washing the cranberries and strawberries. Remove any stems, and chop the strawberries into small pieces. In a large bowl, combine the cranberries and strawberries, then add the ground cinnamon, nutmeg, cloves, ginger, and brown sugar. Stir everything together thoroughly until well-coated.

Transfer the fruit mixture into your slow cooker, ensuring it fits comfortably without overflowing. Spread it out evenly within the pot. Cover the slow cooker with its lid, set it to HIGH, and let it cook for 4 hours.

After cooking, carefully remove the lid and check the fruit mixture. Blend the mixture in small batches to achieve a jam-like consistency, ensuring it is smooth but still slightly chunky.

Transfer the blended Christmas Jam into clean jars. Allow it to cool at room temperature for about an hour before sealing the jars with their lids.