Preheat oven to 375°F (190°C).
In a large skillet, melt butter over medium heat. Add cremini and shiitake mushrooms, cooking for 8-10 minutes until golden brown. Stir occasionally.
Add diced onion and minced garlic to the skillet. Sauté for 2-3 minutes until onion is soft and garlic is fragrant.
In a large bowl, combine softened cream cheese, sour cream, Parmesan, mozzarella, thyme, and Worcestershire sauce. Fold in mushroom mixture. Season with salt and pepper.
Spread mixture into a 1-quart oven-safe dish.
Bake for 20-25 minutes until golden and bubbly.
Garnish with parsley and serve hot with dippers like crusty bread or veggies.