Tip the cooled cooked rice into a large mixing bowl. Add the grated Parmigiano Reggiano, 2 eggs, parsley, salt, pepper, and nutmeg. Mix with a fork until evenly combined and slightly sticky.

Cover and chill the mixture in the fridge for 30 minutes. This firms it up so the croquettes hold together in the oil instead of splitting at the seams.

Scoop about 55 g of the rice mixture (a heaped 3 tbsp) into your palm. Flatten it, press a mozzarella cube into the center, and fold the rice around it, rolling into a small oval log about 6 cm long. Repeat with the remaining mixture, you'll get about 12 to 14 croquettes.

Set up three shallow dishes: one with flour, one with the 2 beaten eggs, one with breadcrumbs.

Roll each croquette in flour and tap off the excess, dip in the egg, then roll in the breadcrumbs, pressing gently so they stick. Line them up on a tray as you go.

Pour the oil into a 24 cm / 9-inch deep pot or Dutch oven, filling about 6 cm deep. Heat to 175 C / 350 F, checking with an instant-read thermometer.

Fry the croquettes in batches of 4 so the oil temperature doesn't drop, for 3 to 4 minutes, turning once, until deep golden brown all over.

Lift out with a slotted spoon and drain on a wire rack. Let the oil return to 175 C / 350 F before starting the next batch.

Serve the crocchette di riso warm, while the mozzarella center is still molten.