Preheat the oven to 425F and line a large baking sheet with parchment paper.
Make the marinade: In a medium bowl whisk together the 4 tbsp olive oil, 2 tsp garlic powder, 1 tsp paprika, 1 tsp ground cumin, 1 tsp onion powder, 2 tsp salt, 1/2 tsp pepper and juice of one small lemon. Remove 2 tbsp of this mixture to another medium bowl and set aside.Add the chicken thighs to the original bowl with most of the marinade and toss them to coat the chicken thighs well. Set aside. In the bowl with the 2 tbsp of marinade, add the halved brussels sprouts and toss together well to combine. Set aside.
Once the oven is preheated, add the chicken thighs to the parchment paper lined baking sheet and put in the oven for 20 minutes.
After 20 minutes, remove the baking sheet from the oven and scatter the seasoned brussels sprouts around the chicken thighs. Put back in the oven for 25-30 minutes or until the chicken is cooked through (165F internal temperature) and the skin is crispy.
While the chicken and brussels sprouts are roasting, make the pomegranate sauce. To a small pot add 1/2 cup pomegranate juice, 1/4 cup honey, 1/4 cup balsamic, zest of one orange, 3 small garlic cloves pressed or grated and 2 tbsp molasses. Heat over medium heat until the sauce starts to bubble / boil and then turn the heat to medium low, cook stirring often, until the sauce reduces by about half and is slightly thicker, about 15-20 minutes. Set aside.
To assemble the final dish, garnish with pomegranate arils (seeds) and then serve the chicken thighs drizzled with the pomegranate sauce.