WHAT YOU NEED

olive oil, for cooking
1.2kg (2 lb 12 oz, about 8) boneless, skinless chicken thighs (about 6), cut into large chunks
salt
freshly ground black pepper
150g (5 ½oz) bacon, cut into lardons
2 brown onions, cut into 1.5cm (5/8 inch) chunks
300g (101/2 oz) Swiss brown mushrooms, halved, or quartered if large
4 garlic cloves, smashed
3 tablespoons plain (all-purpose) flour
500ml (2 cups) dry white wine
250ml (1 cup) chicken stock
2 bay leaves
2 tablespoons finely chopped tarragon leaves
4 thyme sprigs
3 tablespoons crème fraîche
1 sheet all-butter puff pastry, thawed but kept cold
1 egg, lightly beaten, for brushing

Heat a large heavy-based casserole over medium heat and drizzle with olive oil.
Season the chicken pieces well with salt and pepper. Brown the chicken in batches in the pan until golden – about 5 minutes on one side for really golden edges, then just a quick 1–2 minute sear on the other. Set aside.
Add the bacon to the pan and cook until golden and rendered, 8–10 minutes. Add the onion and mushrooms and cook gently until soft and starting to caramelise, 8–10 minutes. Stir in the garlic and cook for another minute. Sprinkle the flour over the onion and stir well to coat, cooking it out for a minute. Pour in the wine, stirring to deglaze the pot, then let it bubble for a minute before adding the chicken stock.
Return the chicken and any resting juices to the pot along with the bay leaves, tarragon and thyme. Bring to a simmer and cook, uncovered, for 20 minutes to reduce slightly. Stir the crème fraîche through, remove the pan from the heat and allow to cool.
Preheat the oven to 220°C (425°F) fan-forced.
Lay the pastry sheet over the pot, tucking it in at the edges if needed. Slash the pastry top with air vents – I like to create actual ribs for extra crisp and sauce release (see the photograph). Brush with beaten egg. Bake, uncovered, for 20–25 minutes or until the pastry is puffed and deeply golden.
Refrigerate in an airtight container for up to 3 days, or freeze for up to 3 months.

HINTS

Keep the pastry very cold until you need it, so it stays light and crisp.
Let the stew cool for 10 minutes before topping with the pastry, otherwise it might melt the pastry before it puffs.
If your sauce feels too thin, let it simmer a little longer before adding the pastry; it should still have a slight soupiness, so it’s not too thick like a standard pie filling.