1: Remove any giblets from the chickens and rinse well inside and out.
2: Make the brine: Place the salt, honey and hot water in a stockpot. Bring to a boil, and whisk until the ingredients are completely dissolved. Whisk in the cold water, cognac, lemon zest, juniper berries, bay leaves, and thyme, and let cool to room temperature.
3: Add the chickens, placing a saucepan, bag of ice, or a dinner plate on top to keep the birds submerged. Brine the birds for 12 to 24 hours.
4: Set up your grill for spit-roasting and heat to medium-high. Arrange the drip pans underneath the grill grate to catch drippings from the roasting birds.
5: Drain the chickens well and blot dry with paper towels. Tuck the wings behind the backs and truss the birds with butcher’s string. Thread the birds from side to side onto the spit, one pointing one direction, one pointing the other. Secure them with the rotisserie prongs.
6: In the meantime, make the garlic sage butter: Melt the butter in a skillet or saucepan over medium heat. Add the garlic and sage leaves; cook until the sage is fried and the butter is aromatic. Keep warm.
7: Place the wood or smoking chips on the coals or in the smoker box. Spit-roast the chickens until darkly browned and cooked through, 60 to 80 minutes—the internal temperature in the deepest part of the thigh should be 165 to 170 degrees. Occasionally baste the birds with the garlic sage butter.
8: Transfer the birds to a platter and let rest for 5 minutes. Remove and discard the trussing string.
9: Carve each bird and serve, if desired, with the Grilled Polenta and the remaining sage garlic butter.