Put the flour and salt in a large bowl.
Mix the milk, egg, oil and sugar together in another bowl.
Pour the milk mixture into the dry ingredients and mix gently.
Put half the mixture in your prepared (greased, lined) slow cooker bowl.
Drop on some spoonfuls of jam.
Top with the rest of the cake batter, then add more spoonfuls of jam on top.
Swirl the jam around with a knife to achieve a pretty effect.
Cook on high with a tea towel under the lid to stop moisture dripping on top. Cook for approx 1.5 hours to 2 hours on high, then check if it is cooked through using a skewer in the deepest part of the cake. If needed cook for another half an hour then check again, repeat as needed.
Turn the cake out onto a rack to cool, or serve it warm right from the pot, with custard or ice cream!