Sift flour and cocoa powder together; set aside. In a food processor, cream butter, salt and sugar. Add the egg and powders in 2 times. Mix until combined and chill for a couple of hours (can be made in advance). Flour countertop, work out half of the pastry – make it supple but still cool, and roll dough out into a 0.12 inch/3mm disk and lightly prick. Make a 8 inch/21cm greased round pan, tart ring or make individual if desired. This recipe can handle 3 tart shells. The dough can be stored a week in the refrigerator or kept frozen for up to 3 months. Blend bake tart shell for 20 minutes at 350ºF/180ºC. Remove pie weights and bake for 10 minutes more; cool.
*To make peanut buter from scratch, look up at Peanut Spread Recipe. Combine peanut butter and melted milk chocolate. Add corn flakes, nuts and chocolate pearls. Spread evenly in the baked tart shell; set aside.
*Gianduja is a mixture made up of hazelnut praline paste and dark or milk chocolate (1 to 1 ratio). Gianduia is denser than Nutella, with a more delicate taste. Gianduia remains an artisan product.
Blend all ingredients together. Spread over the nut-chocolate crunch and leave it to set in a cool area or refrigerator. Make another layer of ganache if desired using a smaller ring lined with acetate or parchment; freeze to harden and un-mold. Top the tart with the frozen ganache and place in the refrigerator to thaw.
Mix 10g sugar with pectin; set aside. Heat up a small pan and make a light brown caramel a sec (dry caramel) with remaining sugar. Stir in butter and add the sugar-pectin or lemon juice and cocoa nibs. Spread hot mixture evenly inside a pastry ring (same size as the top ganache). Bake at 400ºF/200ºC for 10 min max. Remove tart ring and cut into 8 triangles while still warm. Let cool. Slice out Stromboli tart and top each slice with a cocoa nibs tuile. Enjoy!