Preheat your oven to 350°F (175°C). This is an important step as it ensures that the mushrooms cook evenly and the filling gets perfectly melty.
Take the mushrooms and clean them gently with a wet paper towel. This helps to remove any dirt without soaking them.
Carefully remove the stems from the mushrooms and set the caps aside. You can use a small pairing knife or your fingers for this.
Finely chop the mushroom stems. You want them small enough to mix into the filling, but not too small that they lose their texture.
In a medium skillet, heat the olive oil over medium heat. Once hot, add the minced garlic and chopped mushroom stems, sautéing until they are tender and fragrant, about 3 to 5 minutes.
While that’s cooking, take a mixing bowl and combine the softened cream cheese, Parmesan cheese, black pepper, onion powder, and cayenne pepper (if using). Add the sautéed mushroom stem mixture and combine until it’s fully blended.
Now it’s time to fill the mushroom caps. Using a spoon or small spatula, generously fill each cap with the creamy filling. Don’t be shy; you want these to be packed with flavor!
Place the filled mushrooms on a baking sheet, ensuring they’re not overcrowded. This allows them to bake evenly.
Bake in the preheated oven for 15 to 20 minutes. You’re looking for the mushrooms to soften and the filling to heat through, with a lovely golden-brown color on top.
Once done, remove them from the oven and let them cool slightly before garnishing with minced parsley. Serve them warm and enjoy!