Prep the Mushrooms: Preheat your oven to 375°F (190°C). Clean the mushrooms with a damp cloth and gently remove the stems. Set the caps aside and finely chop the stems.

Make the Filling: Heat olive oil in a skillet over medium heat. Add the chopped mushroom stems and garlic, cooking until softened. Transfer to a bowl and mix in breadcrumbs, Parmesan, parsley, thyme, melted butter, salt, and pepper. Stir until combined.

Stuff the Mushrooms: Line a baking sheet with parchment paper. Fill each mushroom cap generously with the prepared stuffing, pressing slightly to secure.

Bake: Arrange the stuffed mushrooms on the baking sheet and bake for 18-20 minutes, or until the tops are golden and the mushrooms are tender.

Serve: Let the mushrooms cool for 5 minutes before serving. Garnish with extra parsley for presentation.