Hummingbird Bakery's Apple and Walnut Cupcakes

According to the book: for 12-16 cupcakes (I made 12 medium size cupcakes and 24 mini

cupcakes)

For the sponge:                           For the frosting:

80g softenend butter                   600g icing sugar
280g caster sugar                       100g softened butter
240g plain flour                           250g full fat cream cheese
1 tbsp. baking powder                 ground cinnamon
1/4 tsp. salt                                12-16 walnut halves
1 1/2 tsp. ground cinnamon
240ml whole milk
2 eggs
200g apples (peeled and cut
in small pieces)
50g chopped walnuts

1. Beat together the butter, sugar, flour, baking powder, salt and cinnamon 

on low speed until the consistency of fine bread crumbs.

2. Whisk eggs and milk and pour 3/4 of the mixture into the dry ingredients. 

Mix on low speed first, pour in the remaining milk mixture and mix on medium 

speed until the batter is smooth.
3. Stir apples and walnuts into the batter.
4. Fill paper cases by about two-thirds and bake the cupcakes for 18-20 

minutes at 190C
5. For the frosting: Beat icing sugar with butter on low speed until 

sandy in texture.
6. Add cream cheese and mix on medium-to-high speed until the frosting is smooth.
7. Decorate the cupcakes with the frosting when they are cooled. Dust them with 

cinnamon and put half a walnut on each.