Add the oil and butter to a deep skillet over medium-high heat. Once the butter has melted, sauté the onion for 4 minutes.
Add in the mushrooms and cook for 5 minutes, stirring occasionally.
Reduce the heat to medium, then stir in the garlic and cook for 30 seconds.
Add in the broth, cream, and gnocchi, and give it a good stir. Once it starts to bubble, let it cook, uncovered, stirring fairly often, until the gnocchi has softened and the sauce has thickened considerably (about 7 minutes). You may need to reduce the heat if it's bubbling a lot.
Stir in the Boursin, then take the skillet off the heat and season with salt & pepper as needed and garnish with chopped parsley if using.
