PROCEDURE:

1. FOR THE DOUGH: In a stand mixer with a paddle attachment, or on a pastry board, knead the butter while still cold, the sugar and a pinch of salt. Then add the egg yolks and mix; add the flour and continue kneading until you have a firm, homogeneous mixture. Form a loaf, wrap it in plastic wrap and let it rest for at least 2 hours in the refrigerator, or overnight.
2. FOR THE FILLING:Boil the rice until it’s well cooked, drain and let cool. In a small saucepan, pour the boiled rice, butter, milk, orange and lemon zests and stir for 5 minutes until the batter is dry and firm. Remove the mixture from the stove and let it rest. In a bowl, lightly beat with a hand whisk the sugar with the previously sifted ricotta. Add the eggs, egg yolks, and cinnamon and continue to mix. Finally add the cooked rice mixture and make it smooth by mixing with a spatula.
3. ASSEMBLY: When the necessary resting time in the refrigerator has passed, knead the shortcrust pastry to make it elastic again, then roll out 2/3 of it with a rolling pin until it is about 5-6 mm thick. Butter and flour a 26-cm-diameter cake pan and line it with the rolled-out shortcrust pastry, leaving a border about 4-5 cm high. Pour the pastiera filling inside and lower the edge of the pastry if necessary. Roll out the leftover pastry, still the same thickness, with a pastry cutter cut out strips and place them interlacing them over the filling, following the classic procedure for tarts.
4. BAKING: Bake the pastiera in a static oven at 175° for 45 minutes. Next, continue baking for another 15-20 minutes raising the temperature to 180°, keeping it monitored during the last 5 minutes. Finally, take it out of the oven and let it cool.
5. DECORATING: Place the pastiera on a serving plate and sprinkle with powdered sugar to taste.

A recipe by @Lucake