3Stir in about three-quarters of the scallions (saving some of the green parts for garnish) and garlic, and cook until softened, stirring frequently, about 3 minutes.
4Stir in spinach, adding in batches if it doesn’t all fit in the pan at once, and ½ teaspoon salt.
5Continue to cook, stirring occasionally, until spinach is wilted, about 5 minutes.
6Stir in stock and bring to a simmer.
7Stir in orzo, lemon zest and remaining ½ teaspoon salt.
8Cover and simmer over medium-low heat until orzo is nearly cooked through and most of the liquid is absorbed, 10 to 14 minutes, stirring once or twice.
9Stir in cheese, peas (if you like) and dill, cover the pan, and cook for another 1 minute, to finish cooking and warm the peas.
10To serve, sprinkle with more cheese and the reserved scallions.