What vegetables go in chicken pie?

The classic line-up

Leek is the definitive partner for chicken in a British pie. It softens into silky ribbons, sweetens the sauce and never fights the meat. Onion does a similar job more cheaply, and many fillings use both.

Carrot and celery bring sweetness and a savoury backbone. Cut them small, around 1cm dice, so they cook through in the same time as everything else. Peas go in last, straight from frozen, and keep their colour through the bake.

Vegetables that need precooking

Anything dense or watery should be cooked before it meets the sauce. Raw vegetables release liquid in the oven and thin a filling you worked hard to thicken.

Mushrooms are the main offender. Fry them in a hot, dry pan until their moisture has evaporated and they have picked up colour, then fold them in. Root vegetables such as carrot, swede and parsnip need 5 to 10 minutes of sweating in butter first.

• Leeks and onions: sweat in butter for 8 to 10 minutes until soft
• Carrots, celery, parsnip: dice to 1cm and soften with the alliums
• Mushrooms: fry hard until dry and browned
• Peas and sweetcorn: stir in frozen at the end
• Spinach: wilt, squeeze dry, then fold through

Vegetables to treat with caution

Courgette, tomato and fresh spinach carry a lot of water and will loosen the sauce unless you cook that moisture out first. Squeeze wilted greens firmly before adding them.

Potato works but changes the character of the pie, making it heavier and more of a complete meal in a crust. If you add it, use a waxy variety in small dice and par-cook it, because raw potato may still be firm when the pastry is done.

Strong brassicas such as broccoli and cauliflower are divisive in a creamy filling. If you use them, blanch briefly and keep the pieces small so they finish tender rather than sulphurous.