I stole this simple dish from Oprah. That's right, right out of her hands. Because I'm awful like that. My advice is to go easy on the flavoring--I found it didn't need much, and it came out superb. I used the rest of the lemon to make a honey lemon hot drink for my sick self.
In a large skillet, heat the olive oil, garlic and rosemary over medium heat. Once the garlic turns fragrant and the rosemary begins to sizzle, remove the rosemary, setting it aside for later.
Add the leeks to the pan, along with a good pinch of salt. Cook, stirring often, until the leeks are soft and sweet but still brightly green, around 5-8 minutes. Tip in the chickpeas, and continue to cook, turning the beans in the oil, for 5 minutes more, at which point the chickpeas should have darkened slightly in color.
Using a microplane or zester, add a few scrapes of lemon zest to the pan, along with a squeeze of lemon juice. Stir gently to combine. Check for seasoning, adding more juice, zest or salt as needed. Return the reserved rosemary sprigs to the pan, and enjoy warm or at room temperature.