1. Preheat Oven: Heat oven to 400°F.
2. Prepare Spices & Chicken: In a small bowl, mix granulated garlic, onion, paprika, nutmeg, salt, and pepper. Place chicken on a cutting board and lightly pound the thicker parts to an even thickness for more consistent cooking. Transfer chicken to a parchment-lined sheet pan, drizzle with 1 tablespoon olive oil, and sprinkle with half the spice mixture.
3. Prepare Vegetables: In a large bowl, combine chopped carrots, parsnips, and beets with remaining olive oil and remaining spice mixture. Toss to coat evenly. Arrange vegetables around the chicken on the sheet pan.
4. Roast: Roast 25–30 minutes, tossing the vegetables halfway through (after ~15 minutes), until chicken is cooked through (internal temperature 165°F) and vegetables are tender and caramelized.
5. Make Green Tahini Drizzle: While chicken and vegetables roast, combine tahini, olive oil, water, garlic, lemon juice, cilantro/parsley, and salt in a food processor or high-speed blender. Blend until smooth. Taste and adjust salt or lemon if needed.
6. Assemble Bowls: Slice or cube chicken. Divide roasted vegetables and chicken among bowls. Drizzle generously with green tahini. Garnish with extra parsley or herbs if desired. Serve immediately.