Put the pasta water on Bring the 2 quarts water to a boil in the pot. Add the ½ teaspoon salt. Meanwhile, drain and rinse the chickpeas, mince the garlic, and zest the lemon before squeezing its juice.

Cook and drain the spinach Prepare the frozen spinach by its package directions, including the stated cooking and standing times. If the label requires cooking the whole package, do that and use a proportionate share based on its original frozen weight. Let it cool just enough to handle, then press out excess water in a sieve or squeeze in a clean kitchen towel. Break the squeezed spinach into small loose pieces.

Boil the orzo Add the orzo to the boiling water and stir well, especially during the first minute. Cook according to its package until tender with a slight bite; taste a few pieces near the end. Before draining, scoop out ¾ cup cooking water. Drain the orzo without rinsing it.

Warm the chickpeas and greens When the pasta is nearly ready, warm the oil in the skillet over medium-low heat. Stir in the garlic for about 30 seconds, until fragrant but not brown. Add the chickpeas, cooked spinach, and 2 tablespoons of the reserved water. Stir gently for 3–4 minutes, until the chickpeas are hot and the spinach is evenly distributed.

Loosen and coat the pasta Add the drained orzo and another 2 tablespoons reserved water. Fold over medium-low heat for 1–2 minutes. If the pasta looks dry or gathers in stiff clumps, add more reserved water 1 tablespoon at a time. Stop when the mixture moves easily under the spoon with a light coating and no puddle.

Finish with lemon Take the skillet off the heat. Fold in the lemon zest, juice, pepper, and parsley if using. Taste before adding more salt. Divide between two bowls and serve promptly; if the pasta tightens before serving, fold in one final small splash of warm reserved water.