Combine 2 L water, 4 cups apple cider, kosher salt, and brown sugar in a pot. Add thyme and peppercorns; heat until dissolved. Cool with 1 L ice water, then brine the chicken for 12-24 hours.

Remove and pat dry the chicken an hour before roasting. Make a compound butter with softened butter, chopped thyme, sage, orange zest, salt, and pepper. Reserve 2 tbsp.

Preheat the oven to 350°F. Slice onion and orange, prepare garlic. Toss olive oil in a roasting pan and add veggies and herbs.

Stuff the chicken with the orange half and thyme, slather with compound butter, and tie the legs with twine.

Pour 1 cup apple cider into the pan, roast uncovered for 1 hour. Add apples brushed with melted butter and glaze with reduced cider after the internal temperature hits 140°F. Continue roasting until it reaches 165°F.

Strain drippings, make a roux with fat and flour, whisk in broth or cider. Simmer, season, and serve chicken with gravy and apples.