Place rack into middle of oven, and preheat to 160ºC fan forced.
Grease and line 24cm round cake tin.
Spread butter over base of tin and sprinkle with the dark brown sugar.
Place the apples cut in eighths in a circle on the base, starting from just inside the rim and working your way around the tin.
Place the 500g of quartered apples into TM bowl and chop 5 sec/speed 6. Scrape down sides of bowl.
Add oil, sugar, eggs and sour cream and mix 10 sec/speed 5. Scrape down sides of bowl.
Add flour, oats, baking powder, bicarb soda, salt and spices and mix 10 sec/speed 5. Scrape around top and sides of bowl, and mix for another 2 sec/speed 5 to ensure all the mix is incorporated.
Pour batter over apples in cake tin being careful not to dislodge them. Bake for 60 minutes, turn tin around and bake for a further 15 minutes or until a skewer inserted comes out clean.
Rest for 20 minutes before removing and placing on a cake rack to cool.
Serve dusted with cinnamon sugar.
Instead of dusting with cinnamon sugar, glaze the top with ½ cup apricot jam warmed with 1 tbsp hot water and pushed through a sieve … spread over the cake whilst it is still warm … it will set as it cools.