4 1/4 Cups low-sodium homemade chicken stock or store-bought broth
4 Tablespoons unsalted butter, divided
1 medium onion, finely chopped
2 garlic cloves, thinly sliced
1 Cup arborio rice
1 1/2 teaspoons kosher salt, plus more
2 oz. finely grated Parmesan (about 1 cup)
2 teaspoons finely grated lemon zest
1 Tablespoon fresh lemon juice
1 teaspoon freshly ground black pepper, plus more
1/2 pound Italian sausage
1/2 pound mushrooms chopped into a very fine dice
2 Tablespoons butter
2 Tablespoons flour or more as needed
1/4 Cup Parmesan cheese
3 oz shredded mozzarella,
2 Cups seasoned breadcrumbs
1/2 Cup all-purpose flour
2 large eggs
Canola oil (for frying; about 6 cups)
Sauces: in cookbook
Bring stock to a simmer in a medium pot over medium heat, then keep warm over low.
Heat 2 Tablespoons 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.
Stir in rice; season with 1 1/2 teaspoons salt. Cook, stirring often, until some of the grains turn translucent around the edges, about 3 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 cup of stock and continue to cook, stirring yet again, until most of the liquid is absorbed, 5–7 minutes. Add remaining 1 1/2 cups stock and cook, stirring often, until rice is cooked through and liquid is mostly absorbed, 9–11 minutes longer. Remove from heat. Stir in Parmesan,1 teaspoon pepper, and remaining 2 Tablespoons of butter. Season risotto with salt.
Spread risotto in an even layer on a parchment-lined rimmed baking sheet. Chill at least 1 hour or overnight (cover risotto with plastic wrap after 1 hour so it doesn’t develop a skin).
Filling: cook and breakup the sausage into fine pieces when almost fully cooked add the mushrooms and cook 4 more minutes, season with salt and pepper and fresh thyme (optional). Add 2 Tablespoons of butter and sprinkle about 2 Tablespoons of flour over the meat mixture until butter is melted. Stir to form a thick paste like consistency, add mozzarella and Parmesan cheese and let cool.
Line another rimmed baking sheet with parchment. Scoop about ¼ cup risotto into your hands and form into a patty about 2 1/2 inches in diameter (it doesn’t need to be perfect!). Place a small teaspoon of meat filling in the center of patty. Carefully pinch and shape risotto so it completely encases the filling, 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 filling. Meanwhile, place breadcrumbs in a shallow bowl. Place flour in another shallow bowl. Lightly beat eggs in a third shallow bowl 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 breadcrumbs, pressing gently to adhere. Transfer to a parchment-lined rimmed baking sheet. Chill balls while you heat oil. Pour oil into a medium heavy pot fitted with thermometer to a depth of 2". Heat over medium until thermometer registers 350°. Carefully lower a few 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.