Begin by preheating the oven to 180C/ 250F/ GM4 and grease & line a 20cmx30cm baking tin
Next mix the spices together in a bowl
Put the demerara sugar into a small bowl, add 1 teaspoon of the mixed spice and stir
Prepare the apples by cutting each one into eight wedges. Remove the core, then slice each wedge into chunks approximately ¼cm thick. Put into a bowl and toss with the lemon juice to prevent browning
Sieve the flour, baking powder, baking soda, salt and spices into a bowl
Using electric beaters, cream the butter and sugar together until pale and fluffy
Add the eggs, one at a time, beating well between each addition. If the batter splits, mix in a spoonful of flour to help bind the ingredients back together
Mix in the soured cream
Add the flour mix and beat, on medium speed, until combined and the batter is smooth. Take care not to overbeat the mixture, as this will lead to a tough sponge
Spoon the batter into the baking tin and use a blunt knife to spread it out evenly
Drain the apple from the juice and scatter over the top of the batter
Reserve 1½ teaspoon of the demerara sugar and sprinkle the rest evenly over the cake
Transfer to the oven and bake for around 30 minutes until the cake is golden, well risen and a skewer poked into the centre comes out clean
Once baked, remove from the oven and sprinkle the remaining sugar over the top. Leave to cool in the tin
Once cool, carefully take out of the tin and remove the baking paper. Cut into 15 pieces using a serrated knife and sharp, clean scissors to cut through any awkward pieces of apple
Wrap in foil and store in an airtight container for up to 5 days