Preheat oven to 160 degrees C. Grease and line the base of a 23cm springform cake pan. Brush base and sides with a little melted butter, then sprinkle with amaretti crumbs and shake pan to coat. Place in the fridge to chill while making the batter.
Mix apple with juice and zest. Ina separated bowl, whisk remaining butter, caster sugar, vanilla and milk. Sift in flour and baking powder and fold in with a woodken spoon. Pour half the batter into the cake pan, then layer half the apple and sultanas on top. Repeat with the remaining batter, apple and sultanas, then top with nuts, brown sugar and cinnamon. Bake for 1 hour 20 minutes or until set but still moist. Cool in the pan for 15 minutes. Then turn out.
Serve warm dusted with icing sugar, with thick cream.