A hearty vegetarian cheesy pie topped with golden puff pastry that feels like a real treat. Use a 28cm/11inch or 3-pint pie dish.
1 large cauliflower,
broken into florets.
2 leeks, trimmed and sliced
knob of butter
200g/7oz button mushrooms, halved
115g/4oz frozen peas
55g/2oz butter
55g/2oz plain flour
450ml/¾ pint hot milk
2 tsp Dijon mustard
115g/4oz mature cheddar, coarsely grated
55g/2oz Parmesan, coarsely grated
salt and freshly ground black pepper
375g ready-rolled puff pastry
1 egg, beaten
Preheat the oven to 200C/180C Fan/Gas 6. Steam the leeks for 4 minutes, then add the cauliflower florets and steam for a further 3 minutes until just tender. Run under cold water to stop the cooking, and drain well.
Melt the butter in a large saucepan over a medium heat. Sprinkle in the flour and stir for 1 minute. Gradually add the hot milk, whisking until thickened. Stir in the mustard, cheddar and Parmesan, then season well with salt and freshly ground black pepper. Leave to cool for 5 minutes.
Fry the mushrooms in a knob of butter until golden. Sesaon and set aside to cool. Mix all the cold vegetables and frozen peas into the cheese sauce, and spoon into the pie dish.
Cut a 7cm/3inch strip from the short side of the pastry. Roll out the remainder and cover the pie dish. Trim any excess, make a small slit in the centre and brush with egg.
Roll out the pastry strip a bit thinner, roll tightly and slice to make long thin strips. Dip them in the egg, and arrange on top of the pie in a random fashion. Bake for about 45 minutes until the pastry is golden.