Step 1

Preheat oven to 160C. Heat oil in a large frying pan and brown chicken in batches (3-4 minutes), then transfer to a roasting pan. Pour off excess fat from frying pan, add vegetables and sauté until tender (4-5 minutes), then deglaze pan with wine and simmer until almost completely reduced (1-2 minutes). Add stock and tarragon sprigs, bring to the boil, season to taste, then pour over chicken. Cover pan with foil and braise in oven until meat falls from the bone (1½-2 hours).

Step 2

Remove chicken from pan, strain braising liquid into a saucepan and boil over medium-high heat until reduced to 400ml (20-25 minutes). Transfer braising vegetables to a bowl and add chopped tarragon. Coarsely shred chicken (discard skin, bones and sinew), add to vegetable mixture and stir to combine.

Step 3

Melt butter in a saucepan over medium-high heat, add flour and stir until sand-coloured (1-2 minutes). Gradually add reduced braising liquid, stirring continuously, then bring to the boil and cook until slightly thickened (1-2 minutes). Add chicken mixture, stir to combine and refrigerate until firm (3-4 hours).

Step 4

Preheat oven to 200C. Roll pastry on a lightly floured work surface to 3mm thick (halve the pastry and roll out in 2 batches), then place on a tray and refrigerate to rest (30 minutes). Cut out six 12cm rounds and six 14cm rounds, and refrigerate. Making a Pithiviers at a time (leave remaining pastry refrigerated), place one small round on a tray lined with baking paper, spoon a sixth of the chicken mixture into the centre to form a mound, leaving a 1cm border, then brush around border lightly with eggwash. Place a large round over the top, pulling gently to cover, press edges to seal, then crimp with a fork. Refrigerate while making remaining Pithiviers, then refrigerate to rest (30 minutes). Make a small hole in the centre of each, brush with eggwash then score tops with the side of a fork. Bake on a tray lined with baking paper until they begin to puff and turn golden (15-20 minutes), then reduce oven to 180C and bake until golden and cooked through (10-15 minutes). Serve hot with minted peas or creamy mashed potatoes.