Make the pasta from the listed ingredients following the method for lasagnette, but cutting the pasta into
Melt the butter in a saucepan, add the flour and gently cook over a low heat for 2–3 minutes, stirring constantly. Add the warmed milk and using a balloon whisk, stir for 5 minutes, season with salt. Make sure there are no lumps in the sauce. Reserve two-thirds of the sauce for later, one-third to mix with the filling.
Slice the mushrooms and cook in
Place a generous spoonful of this mixture on each square of pasta and roll up. Place the cannelloni in a single layer on a well-buttered gratin dish. To the remaining two-thirds béchamel, add the cup of milk and reheat. Pour this béchamel on top of the cannelloni and sprinkle with grated Parmesan and gruyère cheeses. Bake in a hot oven set at 230°C/450°F/gas 8 for 15 minutes.