Polish-Style Roast Chicken

2 whole chickens - 3 1/2 to 4 pounds each
1 onion -- peeled and quartered
4 cloves garlic -- peeled
2 tablespoons sweet Hungarian paprika
2 teaspoons salt - plus more to taste
1 teaspoon freshly ground black pepper - plus more to taste
14 1/2 ounces reduced sodium chicken broth - defatted
1/3 cup vodka
2 tablespoons water
1 tablespoon cornstarch
3 tablespoons finely chopped fresh dill
2 tablespoons sour cream -- optional

Position oven rack in lower third of oven; preheat to 350ºF. Remove giblets. Place hearts, necks and gizzards in roasting pan and reserve livers for another use. With a sharp knife, remove excess fat. Dry insides with a paper towel. With your fingers, loosen skin over breasts and thighs to make pockets, being careful not to tear the skin. In a food processor or blender, combine onion, garlic, paprika, 2 teaspoons salt and 1 teaspoon pepper; puree until smooth.

Spread 1/4 cup onion puree in the bottom of a roasting pan. Place chickens in pan, at least 1 inch apart. Rub 1 tablespoon puree into each cavity and spread remaining puree under skin. Tuck wings back and tie legs. Roast chickens for 20 minutes. Drizzle with 1/4 cup chicken broth and roast for 40 minutes more, basting with pan drippings every 20 minutes.

Tent chickens with aluminum foil and continue roasting for 30 minutes, or until an instant-read thermometer inserted into the thickest part of the thigh, away from the bone, registers 180ºF and the cavity juices run clear. Transfer chickens to a platter and cover with foil to keep warm; leave giblets in pan. Pour pan juices into a bowl and chill in freezer for 10 minutes to bring fat to the surface.

Meanwhile, add remaining chicken broth and vodka to roasting pan and bring to a boil over medium heat, scraping up any browned bits adhering to the pan. Add any juices accumulated on chicken platter. Skim off fat from chilled pan juices. Add juices to roasting pan and return to a boil. Strain juices through a fine sieve into a medium saucepan. Bring to a simmer over medium heat.

In a small bowl, blend water and cornstarch; whisk into simmering gravy. Cook, stirring, until slightly thickened, about 1 minute. Whisk in dill and sour cream, if using. Season with salt and pepper. Carve chickens, discarding skin. Serve with gravy.

Serves 8.