My Apple Streusel Cake

Directions
Preparation:15min  ›  Cook:1hour10min  ›  Extra time:1hour25min freezing  ›  Ready in:2hours50min 

1. Struesel: Process the plain flour, self raising flour, brown sugar and cinnamon. Add the chopped butter and process until ingredients just come together. It should be quite crumbly but don't over-process. Wrap the mixture in plastic wrap and put it in the freezer for about an hour. It needs to be cold but don't freeze it solid.
2. Cake: Preheat the oven to 180 degrees C. Grease a deep cake tin.
3. Beat the softened butter, the lemon rind and caster sugar with an electric mixer until light and fluffy. Beat in the eggs, adding them one at a time. Stir in sifted flour and milk. Pour into your prepared cake tin and bake for about 25 minutes.
4. Apple: Peel, core and slice the apples thinly. Melt the extra butter in a large frying pan. Add the apple slices and cook for about 6 to 7 minutes or until browned. Add the brown sugar and cook, stirring occasionally, for 8 to 10 minutes, the syrup should thicken but your apples shouldn't be overdone. Remember that if you cut your apples thinner it will take less time and if you cut them thicker it may take longer.
5. To Assemble: Remove your cake from the oven when the 25 minutes are up and quickly add the apple syrup mixture of top of it. Make sure the apples are spread evenly over the top of the cake. Take the strusel out of the freezer and crumble it over the top (if it is too cold to crumble with your hands you can grate it) and quickly return the cake to the oven and cook it for another 25 to 35 minutes.
6. When cake is finished leave it in the tin to cool for at least 20 minutes before moving it to a cake rack to cool completely.