1	Process pecans in a food processor until finely ground and transfer to a bowl. Process chocolate in food processor until finely ground and add to pecans. Add cocoa, sugar and butter and, using your hands, work butter into dry ingredients until well combined. Add yolks and ½ tsp sea salt and mix to combine. Cover with plastic wrap and refrigerate until chilled (1 hour).
2	Meanwhile, for candied pecans, bring sugar and 60ml water to the boil in a saucepan, stirring to dissolve sugar. Brush down sides of pan with a wet pastry brush and cook over medium-high heat until caramelised (10-15 minutes). Stir in pecans, transfer pecans to an oiled wire rack with an oiled fork (discard remaining caramel), stand until cool (10-15 minutes).
3	Place a pastry sheet on a chilled baking-paper-lined oven tray. Shape chocolate mixture into a disc, place in centre of pastry, then shape mixture with your hands to form a 22cm-diameter dome, covering pastry up to 5cm from the edge. Brush edges with eggwash, cover with remaining pastry, then trim pastry to a 25cm-diameter circle, pressing around edges to seal. Refrigerate until chilled (30 minutes).
4	Meanwhile, preheat oven to 220C. Pierce a small hole in pastry top for steam to escape, then, with a knife, lightly score from the hole in a pinwheel pattern to decorate. Brush with remaining eggwash, bake until golden and puffed (15-25 minutes). Cool on tray for 20 minutes, then serve with candied pecans and double cream.

Note We prefer to use Carême butter puff pastry. Alternatively, buy a 750gm block of butter puff pastry from your local pâtisserie and roll into two 375gm, 4mm-thick squares. Use a good-quality chocolate such as Lindt or Valrhona.