Preheat the oven to 375 degrees and line a baking sheet with parchment paper.
Remove the stems from the mushrooms and set the caps aside. Finely chop the stems.
Heat the olive oil in a skillet over medium heat. Add the chopped mushroom stems and cook for 3 minutes until they soften. Stir in the minced garlic and cook for 1 minute more.
Remove the skillet from heat. Mix in the breadcrumbs, melted butter, Parmesan cheese, parsley, thyme, salt, and black pepper until everything is evenly combined.
Spoon the filling into each mushroom cap and press it down lightly. Place the filled caps on the prepared baking sheet.
Bake for 20 minutes until the mushrooms are tender and the tops turn golden.