In a large pot, bring salted water to a rolling boil. Add the orzo pasta and cook according to the package instructions until it reaches an al dente texture. Once cooked, drain the pasta and set it aside.
In a generously sized skillet, heat the olive oil over medium heat. Add the finely chopped onion and sauté for 3-4 minutes, stirring occasionally, until the onion becomes translucent. Then, add the minced garlic to the skillet and continue cooking for another minute.
Toss the sliced mushrooms into the skillet. Sauté them for about 5-7 minutes, stirring occasionally, until they are beautifully golden brown.
Add the fresh spinach to the skillet, stirring for about 2-3 minutes until it wilts down.
Pour the vegetable broth and heavy cream into the skillet, raising the heat slightly to bring the mixture to a gentle simmer. Stir in the grated Parmesan cheese until it melts into the sauce. Season with salt and pepper.
Add the drained orzo to the skillet, mixing thoroughly to ensure every piece of pasta is well-coated with the creamy sauce. Let it cook together for an extra 2-3 minutes over low heat.
Remove the skillet from the heat. Garnish with freshly chopped parsley and serve hot.