Bring the salted water to a boil, reduce heat and keep to a simmer.

Set a large saucepan over medium heat, add a drizzle of olive oil. Once hot, add the onions and cook until they become tender. When the onions are soft and translucent, add the rice and toast, stirring often to ensure that the rice is evenly coated in the oil, about 5 minutes. Using a large ladle, add 1 cup of hot water until the rice is just covered, stirring continuously until the water is just above the surface of the rice. Repeat the process, adding one ladle full of water at a time, continuously whisking, until all of the water has been used up and the rice is tender.

When the risotto is al dente, stir in the cubed butter, lemon zest, parmesan and peas. Give it a stir until well incorporated, and the butter and cheese have melted. Give it a taste and adjust seasoning accordingly, adding more salt or pepper as needed. Remove from the heat and transfer to a baking sheet lined with parchment paper. Spread it out into an even layer and let cool to room temperature. You can speed things up if you place it in freezer for about 30 minutes.

Once cooled, gran about 1/4 cup of the mixture and flatten it out on your palm. Place a cube of Mozzarella in the center and then roll into a ball. Place on a baking sheet with a clean piece of parchment paper. Continue forming the rest of the arancini.

Place the flour in a shallow dish. Then whisk the eggs in a separate shallow dish. Finally, combine the panko and plain bread crumbs in a third dish. Bread each arancini by dipping in flour, then in egg and then in bread crumbs; return to the baking sheet.

Fill a heavy-bottomed pot about halfway with vegetable oil. Using a deep-fry thermometer, heat the oil up to 350 degrees F. Once hot, carefully drop in about 3 to 4 arancini at a time (depending on how big your pot is). Fry until deep golden brown, about 2 to 4 minutes. Drain with a slotted spoon and pace on a plate lined with paper towels. Then transfer to a wire rack set over a baking sheet to prevent them from getting soggy. Continue frying the rest of the arancini. Serve with the warmed marinara and a sprinkling of Parmesan and fresh parsley. Enjoy!