In a large skillet, heat the olive oil and butter over medium heat.
Sauté the chopped onion until translucent, about 3 minutes.
Add garlic and mushrooms. Cook for 5–6 minutes, stirring occasionally, until mushrooms are soft and golden.
Stir in the orzo and toast for 1–2 minutes.
Pour in the broth, bring to a boil, then reduce heat to a simmer. Cook uncovered for 10–12 minutes, stirring frequently, until orzo is tender and liquid is mostly absorbed.
Stir in the cream cheese until melted and creamy.
Fold in the spinach and cook until wilted, about 2 minutes.
Stir in Parmesan. Season with salt and pepper. Remove from heat.
Garnish with chopped parsley if you’re feeling fancy. Serve hot.