- Prep Time
- 6 cloves garlic
- 1 lemon, zested, 1/2 juiced
- Salt and pepper
- 7 tablespoons butter
- 1 whole chicken (4 to 4 1/2 lbs.)
- 12 ounces celery root, peeled and cut into small pieces
- 1 1/2 pounds yukon gold potatoes, peeled and cut into 1 1/2-inch pieces
- 2 tablespoons whole milk
- 1 1/2 teaspoons grainy dijon mustard
- 2 scallions thinly sliced
Preheat the oven to 450 degrees . Grate or mince 4 garlic cloves. Combine in a small bowl with the lemon zest, 1 tsp. salt and pepper to taste. In a small saucepan, melt 3 tbsp. butter. Stir 2 tbsp. of the melted butter into the garlic-lemon mixture; set the remaining melted butter aside.
Place the chicken, breast side down, on a cutting board, with the large cavity facing you. Using kitchen shears, start at the open cavity and cut down each side of the backbone; discard the backbone. Open the chicken like a book, then flip over. Press down firmly on the skin side of the breast until you hear the bone crack.
Gently slide your fingers between the skin and flesh of the chicken breasts and legs. Using your fingers, stuff the garlic-butter mixture under the skin, spreading it evenly. Rub the reserved melted butter all over the chicken; season generously with salt and pepper. Place the chicken, skin side up, in a roasting pan and roast until the skin is golden-brown and crisp, or until an instant-read thermometer registers 165 degrees , about 45 minutes. (If the skin starts to brown too quickly, cover the chicken loosely with foil.) Let the chicken rest for 15 minutes before carving.
Meanwhile, slice the remaining 2 garlic cloves. Combine in a saucepan with the celery root. Cover with cold water by 1 inch, season with salt and bring to a boil. Lower the heat and simmer for 5 minutes. Add the potatoes, bring to a boil, reduce to a simmer and cook until the potatoes and celery root are tender, 15 to 20 minutes. Drain well and return to the pot; heat over medium heat until dry, about 1 minute. Remove from the heat, then add the milk, mustard and remaining 4 tbsp. butter; coarsely mash. Stir in the scallions and season with salt and pepper. Drizzle the lemon juice over the chicken and serve with the mash.