Apple Streusel Pie

The weather has been cool these few afternoons & my mind started wandering for desserts again ! I was at a supermarket doing some grocery shopping last week & I noticed a bag of Granny Smith among some apples. Apple pie immediately crossed my mind so I grabbed a bag.
It was until yesterday morning that I finally started working on the pie. There's 10 apples in the bag, just nice for a pie, I like my pie with lots of apples ! My helper will be here only after lunch, so to be able to serve this for lunch, I'll have to peel & cut the apples myself, which I find it time consuming but what to do, the apples are smiling at me ........
I've used a disposable 9 " aluminum foil pie pan, no washing & greasing required.

Pastry :

100g Butter
45g Icing sugar
1/2 Egg
175g Flour
2 Tsp Milk powder

Mix butter & icing sugar till well combined, add egg & cream till smooth. Add in sifted flour & milk powder, mix until well blended.
Refrigerate the dough for 30 mins, roll between 2 sheets of plastic wrap to 3-mm thickness & line the pie pan with the pastry. Prick the pastry all over with a fork.

Filling :

10 Granny Smith apples, cored, peeled & cut into chunks
80g Sugar
20g Butter
60G sultanas
1 Tsp Cinnamon powder

Cook apples with sugar in a saucepan until sligtly softened, discard any liquid in the pan. Add butter, cinnamon powder & sultanas, mix well & set aside to cool.

Streusel Topping :

80g Cold butter
55g Icing sugar
100g Flour
40g Ground almonds
50g Walnuts, chopped

Cut the cold butter into smaller pieces, with fingertips, mix with the other ingredients until coarse paste consistency, refrigerate for 30mins.

Place the apple filling into the pastry shell & sprinkle the streusel topping over the filling. Bake at preheated 190C oven for 35-40 mins or until golden brown.

* I forgot to check the apples while they're cooking so it's a bit overcooked , thus the filling is too mushy this time, I prefer my apples still chunky. I've ommited the walnuts for the streusel topping as I run out of them.