Remove the stems from each mushroom to create space for stuffing, and finely chop the stems.
In a small bowl mash the cream cheese, using a fork. Add the chopped stems, green onions (or cilantro), garlic, black pepper and salt, and mix well.
Preheat the oven to 350 degrees F. Using a little spoon, fill each mushroom cap with the cream cheese mixture. Place mushrooms on a non-stick baking tray (or douse it with a cooking spray to prevent them from sticking). Make sure to leave enough space between each so they don't stick together.
Bake in oven until tops are a little golden, about 30 minutes. Serve immediately.