Preheat the oven to 200°C (400°F/Gas 6). Toast the walnuts on a baking tray for 5 minutes, then chop them.
Following steps 2–3, roll out and line a 25cm (10inch) fluted loose-based tart tin with the pastry. Blind bake the pastry shell, then remove it from the oven. Reduce the oven to 180°C (350°F/Gas 4).
To make the filling, mix together the blue cheese, milk, eggs, egg yolks and cream and season. Pour into the pastry shell and scatter with the chopped walnuts. Bake for 25–30 minutes, or until the filling is just set. Leave in the tin for 5 minutes before serving.