Place the chicken stock in a medium pot and bring to a simmer over medium heat. Once simmering, keep warm over low heat.
Place 2 tablespoons of butter in a medium saucepan over medium heat.
Add the onion and salt and cook until softened, about 4 minutes. Add the garlic and cook for 1 more minute.
Add the rice and stir until the rice is fully coated in the butter and starts to turn translucent around the edges, about 3 minutes.
Add the wine and cook, stirring often, until the pan is almost dry. Ladle in 1 cup of the warm chicken stock until the rice is just covered.
Cook stirring often, until the chicken stock is just above the surface of the rice, keeping the liquid at a consistent low boil. Repeat this process until you have added all of the chicken stock and the risotto is cooked through.
Remove the risotto from the heat and add the Parmigiano Reggiano, lemon zest, remaining butter, peas, pepper, and salt to taste.
Spread the risotto in an even layer on a baking sheet lined with parchment paper. Chill in the refrigerator for 1 to 2 hours.
Scoop the risotto into ¼ cup portions and form into 2-inch balls.
Stuff 2 to 3 pieces of mozzarella into the center of each ball, sealing any holes. Place the risotto balls onto a baking sheet lined with parchment paper and freeze for 10 minutes.
Place the panko breadcrumbs into a food processor and pulse until the crumbs become fine. Transfer the breadcrumbs to a shallow dish.
Place the flour in a separate shallow dish and season lightly with salt and pepper. Beat the eggs in a third separate shallow dish.
Select the Preheat function on the Cosori Air Fryer, adjust temperature to 380°F, and press Start/Pause.
Remove the risotto balls from the freezer.
Dredge each risotto ball in the flour, shaking off any excess. Then, evenly coat the risotto balls with the egg mixture, followed by the breadcrumbs.
Spray the risotto balls evenly on all sides with olive oil spray.
Place the arancini into the preheated air fryer basket.
Set temperature to 380°F and time to 15 minutes, then press Start/Pause.
Remove the arancini when golden brown and serve immediately.