Bake the mushrooms in the oven, cover with foil. This will make the mushrooms juicy and soft. Season generously with salt and black pepper. Pour over with olive oil and brush the entire mushroom, even the sides. Bake for 20 minutes at 225℃ top grill setting.
At this time, sauté the onions in 1/2 tablespoon olive oil for 2 minutes, then add 2 chopped cloves of garlic and sauté for another 1 minute. Add the cherry tomatoes and sauté for about 2 minutes. You can add another 1/2 tablespoon of olive oil if the onion starts to burn. Turn off the heat and remove the pan from the stove.
Place the onion and tomato mixture in a separate bowl. Add grated goat cheese and sun-dried tomatoes cut into strips, mix well.
Remove the mushrooms from the oven and fill them with the tomato and cheese mixture. Bake for 4-5 minutes top grill mode. Do not cover with foil. If desired, sprinkle with cheese, fresh green onions, basil leaves and enjoy!