Preheat oven to 350°F (175°C).

Wash the mushrooms and gently remove the stems.

Finely chop the removed mushroom stems.

In a bowl, combine the chopped mushroom stems, minced garlic, chopped parsley, Parmesan cheese, oregano, bread crumbs, salt, and pepper.

Place the mushroom caps stem side up in a baking dish.

Fill each mushroom cap generously with the prepared mixture.

Add approximately 1/4 inch of water to the baking dish to prevent drying.

Evenly pour olive oil over the filled mushroom caps.

Bake in the preheated oven for 30 minutes, or until the mushrooms are tender and the filling is golden brown.

Serve hot.