Chicken, Bacon & Leek Gratin

Ingredients

• 600 g chicken thighs, trimmed and cut into bite-sized pieces
• 40 g plain flour
• sea salt and freshly ground black pepper, to taste
• 300 g leeks (about 3), thinly sliced
• 1 tsp dried thyme
• 2 garlic cloves, crushed
• 400 ml milk, warmed
• 150 ml double cream
• 40 g butter
• 150 g smoked streaky bacon, cut into lardons
• 1 tbsp Dijon mustard
• 1 tbsp olive oil
• 150 g mature cheddar, grated
• 50 g Parmesan, finely grated
• 1 lemon, zest and juice

Method

1. Heat the oven to 200°C fan (220°C conventional). Blot the chicken well.
2. Fry the bacon lardons in a large frying pan over medium heat for 4–5 minutes until deeply crisp and the fat has rendered into a glossy slick. Lift out with a slotted spoon, leaving the smoky fat behind; that's flavour you've already built.
3. Drop the butter into the same pan and add the leeks. Cook over medium heat for 6–8 minutes, stirring often, until silky and sweet but not coloured. Add the crushed garlic and stir for 30 seconds, just until aromatic.
4. Tip in the chicken in two batches; crowd the pan and the meat will steam in its own juices instead of catching gold at the edges. Cook each batch for 4–5 minutes until lightly golden, then return all the chicken to the pan together.
5. Scatter over the flour and stir for a full minute to cook out the raw, pasty taste. Whisk in the warm milk a splash at a time; patience here is what gives you a glossy sauce instead of lumps; then pour in the cream. Stir in the Dijon and thyme and simmer for 3–4 minutes until the sauce coats the back of a spoon and clings to the chicken.
6. Return the bacon to the pan. Taste before adding more salt because the bacon and Parmesan are already salty. Tip everything into a shallow ovenproof dish, scatter the cheddar and Parmesan evenly over the top, and drizzle with the olive oil.
7. Bake for 20–25 minutes until the top is deeply golden and crisp, the edges bronzed, and the sauce bubbling fiercely up the sides.
8. Rest for 5 minutes so the gratin firms slightly.