In a large 12-inch frying pan, melt the unsalted butter and olive oil together over medium-high heat. Once melted, add in the minced garlic and whole white mushrooms, cooking until the mushrooms are tender—this should take about five minutes.
Reduce the heat to medium and add in the cream cheese cubes to the pan with mushrooms. Stir continuously until the cream cheese has fully melted, creating a creamy base for your sauce.
Lower the heat to medium-low before adding in the grated Parmesan cheese, heavy cream, Italian seasoning, oregano, salt, and ground black pepper. Stir thoroughly to combine all ingredients, allowing them to meld together beautifully.
Let everything simmer for about five minutes while stirring often to ensure it doesn't stick to the bottom of your pan. This step allows flavors to deepen and develop into a luxurious sauce.
Once done simmering, remove from heat and sprinkle freshly chopped parsley over your Garlic Parmesan Mushrooms before serving. This not only adds color but also enhances freshness in every bite.