Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 425 degrees. Wash and dry produce.

Dice potatoes into ½-inch pieces. Place in a medium pot with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-20 minutes.

Reserve ½ cup potato cooking liquid; drain and return potatoes to pot.

Meanwhile, zest and halve lemon.

Pat chicken* dry with paper towels; season all over with salt and pepper.

Lay two slices of prosciutto beside each other on a flat surface. Tightly roll prosciutto around chicken. Repeat with remaining prosciutto and chicken.

Heat a drizzle of olive oil in a large pan over medium-high heat. Add wrapped chicken; sear until browned and crispy, 2-3 minutes per side.

Transfer to one side of a baking sheet. Roast on top rack for 5 minutes (you’ll add the green beans then). (For 4 servings, spread chicken out across entire sheet; roast on top rack until cooked through, 15-17 minutes.)

Once chicken has roasted 5 minutes, remove sheet from oven.

Carefully toss green beans on empty side with a large drizzle of olive oil, lemon zest, and salt. (For 4 servings, leave chicken roasting and toss green beans on a second sheet; roast on middle rack.)

Return to top rack until chicken is cooked through and green beans are tender, 10-12 minutes. TIP: If chicken is done first, remove from sheet and continue roasting beans.

Once cool enough to handle, slice chicken crosswise.

Meanwhile, finely chop chives.

To pot with drained potatoes, add sour cream, half the chives, 2 TBSP butter (3 TBSP for 4 servings), and as much truffle seasoning as you like.

Mash until smooth, adding splashes of reserved potato cooking liquid as needed. Season with salt and pepper.

Heat pan used for chicken over medium-high heat. Add stock concentrate, ¼ cup water (⅓ cup for 4 servings), and lemon juice to taste. Cook until thickened, 2-3 minutes.

Turn off heat; stir in 1 TBSP butter (2 TBSP for 4), salt, and pepper.

Divide chicken, mashed potatoes, and green beans between plates. Top chicken with sauce and remaining chives.