Adjust rack to middle position (top and middle positions for 4 servings) and preheat oven to 425 degrees. Place 2 TBSP butter (3 TBSP for 4) in a small bowl and bring to room temperature.

Pat chicken* dry with paper towels and season all over with salt and pepper; place on one side of a baking sheet (spread out across entire sheet for 4).

Set aside 2 TBSP dressing (4 TBSP for 4) in a second small bowl for serving. 

Brush tops of chicken with ½ TBSP remaining dressing each. Sprinkle with Monterey Jack. Crush crispy onions in their package, then sprinkle over cheese, pressing to adhere.

Wash and dry produce.

Trim, peel, and cut carrots on a diagonal into ¼-inch-thick pieces.

Toss carrots on opposite side of sheet from chicken with a drizzle of oil, salt, and pepper. Roast on middle rack until carrots are tender and chicken is browned and cooked through, 15-20 minutes. (For 4 servings, add carrots to a second baking sheet; roast carrots on top rack and chicken on middle rack.)

Meanwhile, combine softened butter with garlic powder to taste. Season with salt and pepper.

Halve and toast ciabatta. Spread cut sides with garlic butter. Cut each half on a diagonal.

Toss carrots with 1 TBSP plain butter (2 TBSP for 4 servings) until melted. Season with salt and pepper.

Divide chicken, carrots, and garlic bread between plates. Serve with remaining dressing on the side.