Risotto
In a saucepot over medium heat, bring the chicken broth to a simmer. Reduce the heat to low and keep the broth warm.
In a large saucepot or deep skillet over medium heat, melt 2 tablespoons of butter. Add the onion and sauté, stirring often, until soft, approximately 4 minutes. Add the garlic and continue to cook for 1 minute longer until the garlic has softened.
Add the rice to the pot. Season with coarse salt. Toast the rice, stirring often, for about 3 minutes.
Stir in the wine and continue cooking until the wine evaporates, approximately 2 minutes.
Add 1 cup of the warm broth to the rice. Bring to a rolling simmer and cook for about 4 minutes until the broth is absorbed by the rice. You need to stir often. Ladle in another cup of broth and continue simmering for another 6 minutes until the broth is mostly absorbed. Add the remaining broth to the rice and continue to cook and stir until all the broth is absorbed and the rice is cooked but still a little chewy or toothsome, approximately 10 minutes.
Remove the pot from the heat. Add the parmesan, cream, and remaining 2 tablespoons of butter. Stir to combine well until the butter has melted. Season with salt and pepper to taste.
Line a rimmed sheet pan with parchment paper. Spread the risotto over the parchment paper into a single layer and set aside.
Once the rice has cooled, cover it with plastic wrap and place the pan in the refrigerator to chill it for at least 1 hour and up to overnight.
Arancini
Spoon the risotto into a mixing bowl. Reline the sheet pan with clean parchment paper. Scoop out about 1/4 cup of risotto into your hands and form a patty that is about 2-1/2 inches in diameter. Place 2 or 3 pieces of mozzarella in the center of the patty. Form the patty over the cheese and roll the rice into a ball. Place this on the lined baking sheet and repeat until you have about 12 to 15 rice balls.
In a large heavy-bottomed saucepot over medium-high heat, add enough oil to fill the pot about 2 inches deep. Place a thermometer in the oil, clipped to the rim of the pot. Keep an eye on the thermometer. You want the oil to come to 350°F.
Take 3 shallow bowls and fill one with the flour seasoned with salt and pepper. Break the eggs into the second bowl and beat lightly. Place the panko crumbs in the 3rd bowl. Coat an arancini ball lightly with the flour, shaking off any excess. Next, coat the ball in the egg wash. Finally, coat with bread crumbs. Place the ball on the baking sheet and continue until they are all coated.
As soon as the oil is at 350°F, carefully lower 1/3 to 1/2 of the balls into the oil with a slotted spoon or spider. Don’t overcrowd the pot. Fry the balls until golden brown and crisp, approximately 7 minutes. Transfer the cooked arancini to a paper towel-lined platter to drain. Continue cooking in batches.
Serve the warm arancini with or without warmed-up marinara sauce on the side.