Adjust rack to middle position and preheat oven to 400 degrees. Bring 4 cups water (7 cups for 4 servings) and stock concentrates to a boil in a medium pot. Once boiling, reduce heat to low. Wash and dry all produce. Trim and thinly slice scallions, separating whites from greens. Trim mushrooms, then cut into ¼-inch-thick slices.

Heat a drizzle of olive oil in a large pan over medium heat. Add scallion whites. Cook until softened, 1-2 minutes. Add rice and cook, stirring, until translucent, 1-2 minutes. Add ½ cup stock and bring to a simmer. Cook, stirring, until liquid has mostly absorbed. Repeat with remaining stock, adding ½ cup at a time and stirring until liquid has mostly absorbed, until rice is al dente and creamy, 30-35 minutes.

Meanwhile, pat chicken dry with paper towels. Lay two slices of prosciutto beside one another on a flat surface. Tightly roll prosciutto around chicken. Repeat with remaining chicken.

Heat a drizzle of olive oil in a separate large, preferably ovenproof, pan over medium-high heat. Add wrapped chicken to pan and sear until browned, about 2 minutes per side. Transfer pan to oven and roast until chicken is cooked through, about 15 minutes. Let rest a few minutes, then slice crosswise. TIP: If your pan isn’t ovenproof, transfer chicken to a small baking dish before putting in oven.

Meanwhile, quarter lemon. Heat a drizzle of olive oil in a medium pan over medium-high heat. Add mushrooms and season with salt and pepper. Cook, stirring, until tender, 4-7 minutes. Once mushrooms are done, stir into risotto along with garlic herb butter, half the Parmesan, a squeeze of lemon juice, and any resting juices from chicken. Season with salt, pepper, and more lemon juice (to taste).

Divide risotto between plates and sprinkle with scallion greens and remaining Parmesan. Top with chicken. Drizzle with truffle oil (to taste). Serve with any remaining lemon wedges on the side.