Add the flour, cocoa powder, butter, salt, sugar, egg, and cold water to a mixing bowl and use your hands to knead everything into a smooth dough. Wrap the dough in plastic wrap and refrigerate for 1 hour.
Peel a mango, cut it into small cubes, add the sugar and corn starch, and mix well.
Preheat the oven to 350°F. Take the dough out of the fridge, divide it in half, and roll out both halves. Transfer one half to a greased pie pan and lightly press the dough down.
Cut the strawberries in half and place them on the dough in the pie pan. Then add the mango filling and spread it evenly.
Place the other half of the dough on top of the fruit, press the edges down with your fingers, and cut off any excess dough. Poke a few holes in the dough and bake for 50 minutes. Let the pie cool completely after taking it out of the oven.
Melt the white chocolate over a hot water bath and then allow it to cool a little. Cream the butter, stir in the powdered sugar bit by bit, add the cooled white chocolate, and mix everything until well combined. Spoon the frosting into 2 piping bags and use a turntable to create a double spiral on the pie.
Cut the strawberries and mangoes into small pieces, put them in separate pots, and heat the fruit. Puree them, add the dry pectin and lemon juice to each pot, and pour the finished jams into 2 small squeeze bottles. Decorate the top of the pie with the strawberry and mango jam, as shown in the video.