Boil the orzo: Bring a medium pot of salted water and broth to a boil. Add the orzo and cook until al dente, about 7–9 minutes. Reserve 1 cup of pasta water, then drain.

Sizzle the garlic: In the same pot, warm olive oil over medium heat. Add minced garlic and a pinch of red pepper flakes. Cook 30–60 seconds, stirring, until fragrant. Don’t let it brown.

Build the lemon base: Add lemon zest and half the lemon juice to the pot. Stir for 10–15 seconds to lift the flavors off the pan.

Combine with orzo: Return the drained orzo to the pot. Add 1/3–1/2 cup reserved pasta water and toss to coat, forming a light sauce.

Wilt the spinach: Add the spinach in batches, stirring until it just wilts. If the mixture looks dry, add a splash more pasta water.

Finish creamy and bright: Stir in Parmesan and, if using, butter. Add more lemon juice to taste. Season with salt and black pepper. You want it glossy and loose, not soupy.

Serve: Top with extra Parmesan, a drizzle of olive oil, and chopped herbs. Taste and adjust lemon, salt, and pepper right before serving.