Preheat the oven to 180ºC / 350ºF / Gas Mark 4. Bring a large saucepan of lightly salted water
to the boil. Add the cannelloni tubes, return to the boil and cook for 6-7 minutes, or until nearly
tender. Drain and rinse under cold water. Spread out the tubes on a clean tea towel.
Put the ham, spinach and ricotta into a food processor and process for a few seconds until
combined. Add the egg and pecorino cheese and process again to a smooth paste. Transfer to a bowl
and season with nutmeg, salt and pepper.
Grease an oven proof dish with butter. Spoon the filling into a piping bag fitted with a 1cm /
1/2in nozzle. Carefully open one cannelloni tube, stand it upright and pipe in the filling. Place
the filled tube in the dish and continue to fill the remaining cannelloni.
To make the Cheese Sauce, heat the milk to just below boiling point. Meanwhile, melt the butter
in another saucepan. Add the flour to the butter and cook over a low heat stirring constantly, for
1 minute. Remove the saucepan from the heat and gradually stir in the hot milk. Return the saucepan
to the heat and bring to the boil, stirring constantly. Simmer over the lowest possible heat,
stirring frequently, for 10 minutes until thickened and smooth. Remove the saucepan from the heat,
stir in the Gruyere and season to taste with salt and pepper.
Spoon the Cheese Sauce over the filled cannelloni. Cover the dish with foil and bake in the
preheated oven for 20-25 minutes. Serve immediately.