Heat oven to 425⁰ F. In a large bowl, toss together the chicken with 1 tablespoon olive oil, garlic and za’atar. Season well with salt and pepper. Place the shallots and the grapes in a baking pan and gently toss with the remaining olive oil and season well with salt.
Place the chicken skin-side up on the shallots and grapes and tuck a thyme sprig under the skin of the chicken breasts. Roast until the chicken is cooked through (registers 165⁰ F).
Remove from oven. Remove and discard the thyme sprigs. Take chicken off bone (we remove skin) and slice. Put in serving dish and cover with grapes and juice from pan. Scatter with chopped thyme and season with flaky salt.