Combine pimentón de la Vera, pepper, garlic powder, sugar, dry thyme and kosher salt in a small bowl. Rub the chicken inside and out with this mixture, making sure all surfaces and crevices are well spiced. Using kitchen twine, tie the legs together, pull the string around the front and tie around the breast. Cover and refrigerate for a minimum of 2 hours.
Place chicken on a rack in a roasting pan and drizzle with 2 Tbs olive oil. Roast for 30 minutes.
In a large bowl, add the chickpeas and cloves of garlic, season with kosher salt and pepper and drizzle with 1 Tbs olive oil.
Slice the leeks lengthwise and cut the lemons in half transversally.
Remove pan from the oven, carefully lift the chicken and remove the rack. Return the chicken to the pan, and spread the chickpeas around the chicken. Arrange the leeks and the lemons cut side up, drizzle with olive oil and season with a bit of salt and pepper.
Return the pan to the oven and bake for another 30 minutes or until a thermometer inserted between the thigh and the leg reads 170ºF.
Remove pan from the oven, cover loosely with aluminum foil, and let rest for 10 minutes. Cut in portions and serve.