01 - Warm olive oil and butter in a large skillet over medium heat. Add the sliced mushrooms and cook until softened and most moisture has evaporated, approximately 7 minutes.
02 - Stir in minced garlic and cook until fragrant, about 1 minute.
03 - Pour in orzo pasta and stir to coat with the mushroom mixture.
04 - Add vegetable broth, salt, and black pepper. Bring to a boil, then reduce heat and simmer uncovered, stirring occasionally, until liquid is mostly absorbed and orzo is al dente, 10-12 minutes.
05 - Lower heat to medium-low, pour in heavy cream, and fold in grated Parmesan cheese. Stir gently until the sauce becomes creamy and thickens, 3-4 minutes.
06 - Remove from heat, sprinkle chopped parsley over the mixture, and serve immediately.