In a large bowl, whisk the flour, 1 tbsp sugar, salt, and cacao powder.
Add the 1 tbsp olive oil and the 2 tbsp canola oil gradually while whisking, this motion provide coating the flour.
The add the cold cubed butter and mix using pastry blender, don't over mix.
As it shown in the picture, there are some small pieces of butter not fully dissolved. Then Add 1/4 cup + 1 tbsp cold water. Mix the dough gently (don't over mix).
Transfer on working surface, divide the dough into 2 balls.
Wrap them with plastic wrap and refrigerate them for at least 2 hours.
Remove one of the dough from the fridge and leave the second in the fridge.
This dough needs a lot of (flour + cocoa powder) dusting, because the chocolate dough become soft quickly at the room temperature. Work with it as fast as you can.
Place the first chocolate dough layer in the pie tray. I used Non stick Pie Tin with Holes (20 x 2.5cm). Then cover with plastic wrap and place in the fridge until you get the rest of the ingredients ready.
In a large bowl, Peel and slice the apples (not too thin slices) and the 1/2 mango.
Add the chopped dark chocolate
Place 2 tbsp cinnamon, granulated sugar, brown sugar, and lemon. Mix them well.
Roll the second chocolate dough as quickly as you can. To avoid the dough sticking on the working surface add lots of (flour & cocoa) dusting.
Then take the first pie dish from the fridge, place all the filling and 4 small cubed butter on the top. Place the second layer of the chocolate dough on the top of the filling.
Make small straight cuts on the middle-top, the sprinkle with sugar. Bake in preheated oven 200°C / 400°F for about 20 minutes, then rotate the tray and bake for extra 15- 20 minutes (depends on your oven and the pie tray you are using).