FOR BRICK CHICKEN, you will need one or two bricks, wrapped in foil. You can also use another, smaller cast-iron skillet, weighed down with something heatproof. (Do not use cans of food as weights; they will get hot.) This is all about even cooking and really crispy skin.
½ cup (1 stick) butter, at room temperature
2 tablespoons finely chopped fresh sage
1 tablespoon finely choped fresh rosemary
1 lemon, zested and quartered
1 small chicken 3½ pounds
Salt and freshly ground black pepper
Lemon wedges, for serving
1 Preheat the oven to 375°F/190°F
2 In a small bowl, combine all but 2 tablespoons of the softened butter with the sage, rosemary, and lemon zest
3 Using heavy kitchen shears, cut the backbone out of the chicken (or have your butcher do this). Flip the chicken over, then gently push down until it flattens, opening like a book.
4 Working gently, loosen the skin on the chicken (leaving it attached) and ease the seasoned butter in between the skin and the breast. Massage to distribute evenly. Pat the chicken dry, coat with the remaining 2 tablespoons butter, and salt and papper liberally on all sides
5 Heat a 12-inch cast-iron skillet over medium high heat. Carefully lay the chicken, skin side down, in the skillet and weigh it down with foil wrapped bricks. Reduce the heat to medium-low and cook for about 20 minutes
6 With an metal spatula, carefully flip the chicken over so that it's skin side up. Add the quartered lemons to the pan and roast in the oven for 15 to 20 minutes, until the tigh reaches 165°F/75°C
7 Carve as desired. Serve with the pan juices and lemon wedges.