Gently clean the mushrooms with a damp cloth, then carefully remove the stems and set the caps aside.
Finely chop the mushroom stems to create a flavorful filling base.
Heat olive oil in a skillet over medium heat, then add the chopped stems and minced garlic. Cook for about 3-4 minutes until fragrant and softened, stirring frequently.
In a mixing bowl, combine the sautéed stems and garlic with softened cream cheese, grated Parmesan, chopped parsley, thyme, salt, and pepper. Mix until smooth and well incorporated.
Using a small spoon or melon baller, fill each mushroom cap generously with the prepared mixture, pressing slightly to pack the filling.
Arrange the stuffed mushrooms on a parchment-lined baking sheet, then sprinkle with breadcrumbs if using for added crunch.
Bake in a preheated oven at 180°C (350°F) for about 20 minutes, until the tops are golden and bubbling, and the mushrooms are tender when pierced with a fork.
Remove from the oven and let rest for 5 minutes to allow the filling to set slightly and the flavors to meld.
Serve the stuffed mushrooms warm, garnished with extra herbs if desired, and enjoy their crispy, cheesy tops alongside tender, umami-rich mushroom caps.