Heat olive oil and butter in a large skillet over medium-high heat.
Add mushrooms to the pan and cook for 8 minutes until browned and moisture has evaporated.
Incorporate minced garlic and thyme, sautéing for 60 seconds until fragrant.
Reduce heat to medium and pour in the heavy cream.
Simmer for 2 to 3 minutes, then stir in the grated parmesan cheese until the sauce reaches a thickened consistency.
Season with salt and black pepper according to preference.
Garnish with chopped fresh parsley and serve immediately.