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

Dice potatoes into ½-inch pieces. Trim green beans if necessary.

Using your hands, finely crush crispy fried onions in their bag. (TIP: Once crushed, crispy fried onions should resemble breadcrumbs.) Transfer to a small bowl; stir in Monterey Jack.

Reserve 1 TBSP dressing (2 TBSP for 4) in a second small bowl (you’ll use it in step 3).

Place potatoes 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, then drain and return potatoes to pot. Cover to keep warm.

Meanwhile, pat chicken* dry with paper towels and season all over with salt and pepper. Place on one side of a baking sheet. (For 4 servings, spread chicken out across entire sheet.)

Evenly spread tops of chicken with a thin layer of reserved dressing. Mound coated sides with onion crust, pressing to adhere (no need to coat the undersides).

On opposite side of sheet from coated chicken, toss green beans with a drizzle of olive oil, salt, and pepper. (For 4 servings, add green beans to a second sheet; roast green beans on top rack and chicken on middle rack.)

Roast on middle rack until chicken is cooked through and green beans are browned and tender, 18-22 minutes. TIP: Check chicken periodically—if the crust browns too quickly, loosely cover with foil. Additionally, if green beans finish before chicken, remove from sheet and continue roasting chicken.

Meanwhile, mash potatoes with sour cream, 2 TBSP butter (4 TBSP for 4 servings), and a big pinch of salt until smooth, adding splashes of reserved potato cooking liquid as needed. Taste and season with salt and pepper.

Divide mashed potatoes, green beans, and chicken between plates. Serve with remaining dressing on the side.