Step 1

Mix chiles, oil, lemon zest, lemon juice, and garlic in a small bowl to combine.Do Ahead: Sauce can be made 12 hours ahead. Cover tightly with plastic wrap and chill.

Step 2

Bring stock to a simmer in a medium pot over medium heat, then keep warm over low.

Step 3

Heat 2 Tbsp. butter in a medium saucepan over medium. Add onion and cook, stirring often, until softened but not browned, 4–5 minutes. Add garlic and cook, stirring constantly, until softened but not browned, about 1 more minute.

Step 4

Stir in rice; season with 1½ tsp. salt. Cook, stirring often, until some of the grains turn translucent around the edges, about 3 minutes. Add wine and cook, stirring often, until pan is almost dry, about 2 minutes. Ladle in 1 cup warm stock, bring to a simmer, and cook, stirring often, until liquid is absorbed, about 4 minutes. Ladle in another 1 cup stock and continue to cook, stirring yet again, until most of the liquid is absorbed, 5–7 minutes. Add remaining 1½ cups stock and cook, stirring often, until rice is cooked through but toothsome and liquid is mostly absorbed, 9–11 minutes longer. Remove from heat. Stir in Parmesan, cream, lemon zest, lemon juice, 1 tsp. pepper, and remaining 2 Tbsp. butter. Season risotto with salt.

Step 5

Spread risotto in an even layer on a parchment-lined rimmed baking sheet. Chill at least 1 hour or up to 4 (cover risotto with plastic wrap after 1 hour so it doesn’t develop a skin).

Step 6

Line another rimmed baking sheet with parchment. Scoop about ¼ cup risotto into your hands and form into a patty about 2½" in diameter (it doesn’t need to be perfect!). Place 2–3 pieces mozzarella in the center of patty. Carefully pinch and shape risotto so it completely encases the cheese, then roll into a 2" ball. Your hands might get messy, and the balls may be slightly misshapen (they’ll firm up later). Place on prepared baking sheet. Repeat with remaining risotto and mozzarella. Freeze balls 10 minutes.

Step 7

Meanwhile, pulse panko in a food processor or place in a ziptop plastic bag and crush with a rolling pin until finer crumbs form. Transfer to a shallow bowl. Place flour in another shallow bowl. Lightly beat eggs in a third shallow bowl to blend; season all bowls with salt and pepper. Working one at a time, dredge balls in flour, shaking off excess. Transfer to bowl with egg and turn to coat, letting excess drip back into bowl. Coat with panko, pressing gently to adhere. Transfer to a parchment-lined rimmed baking sheet. Chill balls while you heat oil.

Step 8

Pour oil into a medium heavy pot fitted with thermometer to a depth of 2". Heat over medium until thermometer registers 350°. Carefully lower half of rice balls into oil with a slotted spoon or spider and fry until deeply golden brown, 6–8 minutes. Transfer to paper towels to drain; season with salt. Repeat with remaining rice balls. Serve warm with sauce alongside.