• Place 1 chicken breast at a time on a large piece of plastic wrap; sprinkle the meat with a few drops of water. Cover with another piece of plastic; flatten with a rolling pin or heavy frying pan to about ½-inch thickness. Remove the plastic. Transfer the chicken to a plate, pat dry with a paper towel, and season with salt and pepper.
• On a plate or shallow bowl, season the arrowroot powder with salt and pepper and spread in an even layer.

Dredge the chicken in the arrowroot powder, turning to coat; shake off any excess.
In a large frying pan over medium-high heat, warm 2 to 3 teaspoons [1 to 2 TBL] oil. Working in batches if needed, add the chicken and cook, turning once, until lightly browned and cooked through, 3 to 4 minutes per side. Transfer to a plate to rest. Add more oil between batches if needed. Do not clean the pan. While the chicken cooks and rests, prepare the greens.

• Trim the root end from the leek; cut the leek in half lengthwise, then crosswise into ¼-inch-thick half-moons. Rinse well.
• Finely chop, press, or grate enough garlic to measure 1½ teaspoons [1 TBL]; set aside half for the sauce.
• Set aside half the vegetable broth for the sauce.

In another large frying pan over medium heat, warm 2 to 3 teaspoons [1 to 2 TBL] oil. Stir in the leek and half the garlic; cook, stirring occasionally, until starting to soften, 2 to 3 minutes. Working in batches if needed, stir in the greens and cook until just wilted, 1 to 2 minutes. Add ½ cup [1 cup] vegetable broth; bring to a boil, reduce to a simmer, and cook, stirring occasionally, until the greens are tender and the broth is thickened, 3 to 5 minutes.
While the greens cook, prepare the remaining ingredients.

• Juice half the lemon; thinly slice the remaining half. [Juice 1 lemon; thinly slice the remaining lemon.]
• Coarsely chop the olives.
• Strip the parsley leaves from the stems; coarsely chop the leaves. Set aside half for garnish.

In the same pan used for the chicken, warm 1 teaspoon [2 tsp] oil over medium-high heat. Add the lemon slices and cook, turning once, until lightly browned, 2 to 4 minutes. Stir in the olives and remaining garlic; cook until fragrant, about 1 minute. Transfer the lemon slices to a plate. Add the remaining broth, 1 tablespoon [2 TBL] lemon juice, and 2 tablespoons [¼ cup] white wine or water; season with salt and pepper. Bring to a boil, reduce to a simmer, and cook, stirring occasionally, until thickened slightly, 2 to 3 minutes. Stir in half the parsley. Add the chicken and cook, spooning with the sauce, until warmed through, 1 to 2 minutes.

Transfer the chicken and greens to individual plates. Spoon the sauce over the chicken, garnish with the lemon slices and remaining parsley, and serve.