Trim and brush the mushrooms. Don’t rinse them with water. Remove the stems (use them for another recipe like soups or salads) and place the cleaned mushrooms in a large non-stick pan. Season with pepper and salt. Also add 5 tablespoons of water and a tablespoon of olive oil.
Place the pan over high heat until the mushrooms start to sizzle, then turn the heat lower to medium. Bake the mushrooms for about 5 minutes. Then carefully turn them over. Add 3 more tablespoons of water and a tablespoon of olive oil. Put a lid on the pan and bake the mushrooms for 10 more minutes. Add extra water if necessary. In the end the mushrooms should be soft and golden.
Take the cooked mushrooms off the heat and let them cool down a little. In the meantime make some fresh garlic butter. Peel the garlic cloves and mash them up into a puree under the blade of your knife. Chop the fresh parsley very finely. Combine the soft unsalted butter, mashed garlic puree and chopped parsley. Season with a pinch of pepper and salt.
Stir the soft butter well for a minute.
Place the baked mushrooms in a baking dish and fill the stem cavities with a good portion of the fresh made garlic butter.
Place the baking dish with the mushrooms in a preheated oven at 400°C (200°C) for about 15 minutes. Sprinkle with extra chopped parsley right before serving.