To make the stewed apples, put the chopped apples in a wide pan with the butter, spices, sugar and rum and cook on medium heat for 20, stirring occasionally.
To make the topping, mix all the ingredients in a bowl and set aside.
Cook the fruit till the chunks are soft but not disintegrating and till all the juice has cooked off. Drain if required and set aside to cool.
Preheat the oven to 180°C, lightly grease a 20-cm springform cake pan and line the bottom with baking parchment.
Cream the butter and sugar with an electric mixer on high speed till the mixture is pale and fluffy (about 2 mins)
Now beat in the the egg yolks one at a time.
Stir in the vanilla and half of the milk and flour, mix and stir in the remaining milk and flour.
Mix in the stewed apples with a gentle hand.
In a separate, clean bowl beat the egg whites till they form soft peaks. Gently fold into the batter taking care not to overmix.
Pour the batter into the prepared pan, tap gently to release any pockets of air, spread the walnut topping evenly to cover the surface of the cake and bake for 45-50 minutes until done. Check for doneness by inserting a toothpick or skewer into the cake. If it has any wet batter clinging to it, bake the cake for 5-10 more minutes. Cover the cake to ensure the top doesn't burn.
Rest the cake in the pan outside the oven for 10 minutes before un-molding, then cool on a wire rack.