In a mixing bowl, combine olive oil, sumac, crushed garlic, lemon zest, brown sugar, kosher salt, black pepper, cinnamon, and allspice. Coat the chicken thighs evenly in the mixture and let marinate for at least 30 minutes or overnight.

Preheat your oven to 400°F (200°C). Prepare your baking sheet lined with parchment paper or lightly greased.

On the prepared baking sheet, place the plums and shallots in a single layer. Drizzle them with olive oil and add honey, kosher salt, cinnamon, and allspice. Toss together until well-coated.

After marinating, arrange the chicken thighs atop the plum mixture, skin side up. Tuck bay leaves around the chicken.

Slide the baking sheet into the preheated oven and roast for 35-45 minutes until the chicken is golden brown and cooked through.

Once roasted, remove from the oven and let rest for 5 minutes. Garnish with fresh thyme before serving.