Let rice cool for 25 minutes after cooking, then stir in 1 teaspoon kosher salt. Preheat oven to 400 degrees. Coat a foil-or parchment-lined baking sheet liberally with olive oil.
Meanwhile, in a large bowl, stir shredded fontina and provolone cheeses, grated Parmesan cheese, ricotta cheese, eggs, parsley, remaining salt, black pepper, and chili flakes (if using) until well combined. Add cooled rice and peas and stir until mixture is homogenous.
Oil a 1/4-cup measuring cup, then scoop rice mixture and pack with your fingers. Unmold rice mixture and coat on all sides with panko breadcrumbs. Set on prepared baking sheet. Repeat with remaining mixture.
Drizzle arancini with olive oil and bake for 25 minutes.
SPICY TOMATO SAUCE
While the arancini are baking, bring crushed tomatoes, chopped garlic, olive oil, and Calabrian chiles (or flakes) to a boil in a medium pot, then reduce heat and simmer, stirring often, for approx. 35 minutes. Keep warm until ready to serve.
Serve arancini with a side of spicy tomato sauce and a dusting of extra parmesan cheese and fresh basil, if desired.
Recipe and photo courtesy of USA Rice via @Lisathompson in partnership with USA Rice and TheFeedfeed.