Brine the chicken 12 to 24 hours before roasting. Prepare the brine by adding 2 L of water, 4 cups apple cider, 1 cup kosher salt, and brown sugar to a large pot. Tie 3-4 sprigs of thyme and add to the brine with the peppercorns. Heat until dissolved.

Add 1 L of ice water to a large bin or pot. Pour the brine mixture into the ice water to cool. Submerge the chicken breast side down, cover, and refrigerate for 12 to 24 hours.

An hour before roasting, remove the chicken from the brine, discard the brine, pat dry, and air dry at room temperature for 1 hour.

Prepare the compound butter by mixing softened butter, finely chopped thyme, sage, orange zest, ? tsp kosher salt, and ? tsp pepper in a small bowl. Set aside 2 tbsp of the mixture.

Preheat the oven to 350? F. Prepare the roasting pan with thick slices of onion, sliced orange halves, garlic cloves, and sprigs of thyme and sage. Drizzle olive oil in the pan and set a rack on top.

Place the chicken on the rack, stuff with the remaining orange half and thyme, and rub the chicken with the remaining compound butter. Tuck the wings under and tie the legs with twine.

Add 1 cup of apple cider to the roasting pan, roast uncovered for 1 hour, checking for uneven browning.

Cut the apples in half, melt 1 tablespoon of compound butter, and after 1 hour, nestle the apples around the chicken with the cut side up. Brush the apples with the melted butter.

Continue roasting for another 30 to 45 minutes, preparing the reduced cider and maple glaze by boiling the remaining 1 ? cups of apple cider until reduced by half. Whisk in maple syrup and remaining compound butter, then boil for a couple more minutes.

After 1 ? to 1 ? hours, check the chicken's temperature at the thick part of the breast. When reaching around 140 deg F, brush the chicken with the glaze, roast for another 10 minutes, and repeat glazing.

Roast until the chicken reaches at least 165 deg F and the juices run clear. Transfer chicken and apples to a platter, tent with foil.

Prepare the pan gravy by straining juices into a measuring cup, reserving about ? cup of fat. Heat the roasting pan over medium-high heat, add flour to make a roux, then gradually whisk in the remaining pan juices to reach about 3 cups. Season with ? tsp kosher salt and ? tsp pepper, strain into a gravy boat.

Carve the chicken into pieces and serve with apples and pan gravy.