Prepare pasta brisèe: pour the flour into a large bowl, add salt, make a hole in the center and add butter. Start working the dough by rubbing it in your hands to make it sandy. Add te water little by little, always working with hands and kneading, transferring yourself on a floured work surface, for 5 minutes until a smooth and homogeneous dough is obtained. Form a ball, wrap it in plastic wrap and let it rest in the fridge for 40 minutes. Prepare the cream in the meantime: cut the onion into thin slices and put them in a pan with the oil, fry, salt and add the Jerusalem artichokes, peeled, washed and thin slices with the mandolin.
Cook for a few minutes, add the milk, a pinch of salt, pepper, nutmeg, cover with the lid and cook over low heat for 25 minutes. Switch off and keep aside. Prepare the bechamel: heat the milk in a saucepan. Separately, melt butter, add flour all at once and mix vigorously with a hand whisk. Pour in the wire, always mixing with the whisk, the milk on the mixture of flour and butter and bring to the boil, cook for 5 minutes and turn off. Let it cool. Cook the pasta al dente in plenty of boiling salted water. Drain and spread the rigatoni, gently so as not to break them, on a cloth. Cut the mozzarella di bufala into very small cubes.
Add to the Jerusalem artichokes 100g of bechamel, pour it all in the blender and blend to obtain a soft cream. Add to the 2/3 of the cold cream half mozzarella and stir. Roll out the pasta brisèe in a thin disk and use it to cover a buttered and floured 22cm baking pan. Pour a few tablespoons of bechamel on the bottom and spread it to cover the whole surface. Arrange the rigatoni, standing next to each other in the shell of pasta and fill them with the cream of Jerusalem artichoke and buffalo inserted in a sac a poche. Put a few cubes of mozzarella on top of each rigatone.
Stem the remaining bechamel with hot milk so as to make it very fluid. Pour a few tablespoons over the rigatoni, complete with grated parmesan, cover with aluminum and cook in a preheated oven at 200 degrees for 30 minutes. Remove the aluminum and continue cooking for another 10-15 minutes until the rigatoni are well-au gratin. Remove from the oven and serve with the remaining warm cream. Tip: If you like best, you can also prepare single-portion versions using the disposable aluminum molds or prepare two smaller trays (from 2).
a cura di Con un Poco di Zucchero.