1. For Making Pie Crust :- Cut cold unsalted butter into cubes.
2. In a bowl mix the flour with icing sugar.
3. Then add butter cubes.
4. Now incorporate butter into the flour and sugar .
5. Bring this flour together using chilled water.
6. Cover with a cling wrap and refrigerate for 1 hour.
7. After 1 hour take the dough out from refrigerator, unwrap it and divide into 2 portions.
8. Now sprinkle some flour on the work bench and roll them with a rolling pin.
9. Once those dough's are rolled properly, transfer one of them to a pie dish and set aside.
10. Now cut long strips from the second one and set aside.
11. For Making Butter Chicken :- Marinate the chicken pieces with salt, ginger garlic paste,1 teaspoon cumin powder,1 teaspoon coriander powder,1 teaspoon red chilli powder and 1 teaspoon lemon juice for 5 minutes.
12. Heat oil in a pan,add in marinated chicken and cook for 6-7 minutes.
13. When done take out in a bowl and set aside.
14. Now heat butter into the same pan,add in diced onion and cook for 5-6 minutes or until soft.
15. Now add in diced green chillies and cook for 2 minutes.
16. Now add in tomato paste, give a nice stir and cook for 2 minutes.
17. Add in salt,1 teaspoon chili powder,1 teaspoon cumin powder and 1 teaspoon garam masala ,mix well.
18. Now add heavy cream into it and mix well.
19. Cook for 2 minutes.
20. Add in cooked chicken and mix.
21. Now add in 1 teaspoon sugar and cook for another 2 minutes.
22. Now sprinkle chopped coriander leaves and mix.
23. Put off the flame when done and let it cool.
24. Assembling :- Put this cooled Chicken mixture to pastry,patting it down lightly with a spoon to remove any dead spaces and apply egg white at the surface.
25. Now place the long strips vertical and horizontal directions over the pastry by applying egg mixture.
26. Pre-heat oven for 200° C.
27. Bake it for 40 minutes.
28. When done take it out from the oven.
29. Let it cool for 5 minutes.
30. Slice and serve.