Sauté the Aromatics: In a large skillet or pot, heat 2 tablespoons extra virgin olive oil over medium heat. Add 1 yellow onion (chopped) and cook for 3-4 minutes, until softened. Stir in 3 cloves garlic (grated) and cook for another 30 seconds.
Cook the Mushrooms: Add 1 pound mushrooms (sliced) and sauté for 5–7 minutes until browned and most of the moisture evaporates. Season lightly with salt and pepper.
Toast the Orzo: Stir in 1½ cups orzo pasta and toast it for just a minute.
Simmer until Tender: Pour in 4 cups vegetable broth and bring to a gentle simmer. Reduce heat to low, cover, and cook for 5 minutes, stirring every couple of minutes to prevent sticking, until the orzo is almost cooked and most of the liquid absorbed.
Stir in Peas and Cheese: With the heat still on low, stir in 1 cup frozen peas and cook for 1–2 minutes until bright and warmed through. Then, turn off the heat and immediately stir in ¾ cup grated parmesan, 3 tablespoons unsalted butter, 2 tablespoons fresh parsley, the grated zest of 1 lemon, and a squeeze of its juice, if using.Stir until creamy. Taste and season with more salt and pepper as needed.
