Place chicken, onions, garlic, lemon, allspice, cinnamon, and oil in a large bowl. Toss to coat.
Place chicken mixture on a rimmed baking sheet and roast until chicken is browned and cooked through, 35-40 minutes.
For sauce— pulse garlic, tahini, lemon juice, and water in a food processor, adding more water if needed, until smooth and creamy. Season with salt to taste.
Melt butter in a small skillet over medium-high heat. Add pepitas and cook, stirring often, until butter foams, then browns, and nuts begin to brown.
Serve chicken with roasted onion and lemon, topped with pepitas and garlic tahini sauce.
Health Benefits of Roasted Chicken Legs with Garlic Tahini Sauce
Chicken has an incredible amount of protein for its low calorie content. Chicken is also loaded with essential vitamins and minerals, especially B vitamins, which are helpful in preventing cataracts and boosting energy and immunity.