Preheat the oven to 180º C. Line a baking sheet with aluminum foil.
In a small bowl, mix the melted butter, finely chopped garlic, balsamic vinegar, rosemary and parsley.
Put the mushrooms in the bowl and mix to make sure all the mushrooms are coated. Then place them on the baking sheet a little apart from each other. Season with some salt and pepper to taste.
Bake for 15 to 18 minutes, until golden brown and soft.