Cook chicken legs in chicken stock for 45 min. Remove chicken, cool for 10 minutes on tray, and shred off meat. Continue to cook and reduce chicken stock to 500g. Prepare veggies, and clean and chop mushrooms. Throw mushroom trimmings in the reducing chicken stock. In a hot skillet, sweat shallots, carrot and celery with butter for 5 minutes on medium heat. Add mushrooms and cook for 3 minutes more. Add flour and cook for a minute. Pour in the reduced chicken stock and the heavy cream, give a good stir and cook for 10 minutes on low heat; covered. Add the shredded chicken, the blanched English peas. Season with the lemon confit, salt and ground black pepper. Add some chopped fresh herbs and cheese if desired. Keep warm. The chicken supreme sauce can be refrigerated for up to 3 days.
For the inverted puff pastry recipe: look up for The Apple Turnovers recipe. One recipe will hold 12 vol-au-vent. Dust work surface with flour and roll out puff pastry into a generous 1/4inch (1cm) thick rectangle. (If using store bought puff pastry, superimpose 2 sheets of pastry to match the desired thickness and gently brush with water to seal. Readjust the thickness with the rolling pin. Refrigerate dough for 30 min to relax before cutting into circles. Then divide into nine ≈ 4inch (10cm) rounds using a fluted cookie cutter. Save scraps for later use such as pies, mille-feuille etc.. Arrange disks onto a baking tray lined with a moistened silicone mat or parchment paper (it prevents pastry moving around). With a smaller plain 2.4''/6cm diameter cookie cutter, make a round center cut almost all away through. Brush tops with egg wash and chill for 30 minutes. Brush with egg wash again and score (optional). Refrigerate an hour before baking or overnight. To freeze vol-au-vent: place them in the freezer overnight or until it has completely hardened. Store in a sealed freezer bag and keep frozen for a few weeks or sous-vide for up to 12 months.
Preheat oven to 325ºF/160ºC. Place two 1.75''/4.5cm height pastry rings or something similar and ovenproof that can hold an upside down draining grate. This allows vol-au-vent to rise evenly. Bake vol-au-vent for 45 minutes. Turn off oven and leave pastry shells to dry out for 15 minutes. Remove from oven and let cool. If using a convection oven, baking time may be shortened.
Carefully, slice off top from each vol-au-vent following the round mark. Fill each vol-au-vent generously with the hot chicken supreme sauce, put tops back on – Bon appétit!