3 garlic cloves, finely chopped or crushed
1 leek, washed and sliced into rounds
1–2 heaped tsp wholegrain mustard
salt and freshly ground black pepper
dash olive oil
1 vegetable stock cube
250g/9oz cream cheese or crème fraîche
milk, to brush the top
1 sheet ready-rolled puff pastry (320g/11½ oz)
3 chicken breasts, roughly chopped