Pre-heat the oven to 180°C.
Grease and line a 10 inch x 6 inch rectangular baking tin.
Combine the self-raising flour, butter, eggs, vanilla extract and sugar in a large mixing bowl for the cake batter. Beat using an electric hand-held whisk for 1-2 minutes until smooth. Fold in the walnuts. Spoon into the prepared cake tin and bake for 20-25 minutes until risen; remove when a cake tester comes out clean when inserted into the centre of the cakes.
Remove from the oven when ready. Spread the top of the cake with the apricot jam, then sprinkle over the cranberries and then walnuts so that they stick to the cake.
Increase the oven to 200°C.
Return to the oven for 8-10 minutes until the cranberries start to darken in colour. Remove and allow to cool a little before turning out of the tin and serving.