Wrap the garlic in foil, then roast at 425F for 45 minutes until the garlic is very tender. Remove from the oven, and let cool.

Meanwhile, poach the chicken. In a soup pot, cover the chicken by ½ inch with the stock or water with the bouillon. Bring to a boil, then reduce to a simmer and cook through gently, 20 minutes for bone-in chicken and 10-15 for boneless. Remove to a plate when cooked and let cool; shred the chicken when you can handle it. Pour the cooking liquid into a bowl.

Return the soup pot to medium-high heat with a drizzle of oil, the leeks, and celery. Cook for 3 minutes, stirring, until the veggies soften slightly. Add the kale to the pot. Cut the garlic heads in half crosswise and squish the roasted cloves into the pot with a sprinkle of salt. Stir the veggies all together for 2-4 minutes until the kale wilts just slightly, then add the chicken, cooking liquids, and lemon juice to the pot.

Stir the soup, and taste. Add more water or stock for a brothier soup, and salt and pepper to your taste. Let simmer for 10 minutes, then serve!