Pai Ayam dan Daun Bawang

Bahan-bahan (5 porsi)

• 50 g / 3 1/2 tbsp unsalted butter (, divided)
• 750 g / 1.5lb chicken thighs (, skinless, boneless, cut into 1.8 cm / 3/4" bite size pieces (Note 1))
• 1/4 tsp each black pepper and cooking salt ((kosher salt))
• 80 g / 3 oz streaky bacon (, chopped into 1cm / 0.4" squares (Note 2))
• 2 leeks ((Note 3))
• 2 celery stems (, sliced 4 mm / 0.2" thick (cut thick end in half lengthways first))
• 2 g arlic cloves (, finely minced)
• 1/3 cup chardonnay (or other dry white wine (Note 4))
• 1/4 cup flour ((plain / all-purpose))
• 1 tbsp dijon mustard ((Note 5))
• 2 thyme sprigs ((or 1/2 tsp dried thyme))
• 2 bay leaves ((preferably fresh, else dried))
• 1 cup chicken stock / broth (, low sodium)
• 1 cup thickened / heavy cream ((or any full-fat cream, or sub milk for lower fat))
• 1/2 tsp cooking salt / kosher salt
• 1/4 tsp black pepper
• 2 x 20cm / 8" frozen butter puff pastry sheets (, or single sheet large enough to cover baking dish, 360g / 12 oz (Note 6))
• 1 egg (, yolk and whites separated, lightly whisked)