1 (5 to 6-pound) roasting chicken
Kosher salt and freshly ground black pepper
2 heads garlic, cut in 1/2 crosswise
1 lemon, halved
1/2 large Spanish onion, thickly sliced
4 carrots cut diagonally into 2-inch chunks
2 large Yukon gold potatoes, cut into 6 pieces
4 tablespoons butter, melted