1-2tablespoons freshly squeezed lemon juice, as desired
4-5 cupstightly packed chopped spinach, chard, kale, broccoli rabe, or another leafy green
Preheat your oven to 400F. Lightly drizzle the garlic heads with olive oil. Wrap each head in foil and roast for 45 minutes, or until the cloves are becoming caramelized and the garlic is very fragrant.
Heat the olive oil in a large pot over medium heat. Add the onion. Cook for 5-7 minutes, stirring often, or until the onion is tender and clear. Add the chickpeas, broth (or broth + water), salt, and pepper.
Transfer the chickpeas and broth to a powerful blender. Squeeze the roasted garlic cloves from both heads into the blender, too. Blend on high till the mixture is very smooth, taking precaution with spattering (the soup will be very hot). You can do this in batches if your blender is on the small side. You can also use an immersion blender.
Transfer the pureed soup back to the pot and bring to a simmer. Add the greens and cook for another 7-10 minutes, or until the greens are very tender. Stir in the lemon juice. Taste, season as desired, and serve!
If you like, you can roast the garlic 1-3 days ahead of time and store it in the fridge until you're ready to blend.