01 -
Preheat oven to 375°F. Line a rimmed baking sheet with parchment or foil and set aside.
02 -
Clean mushrooms by removing stems so that only the caps remain. Dice mushroom stems into small pieces.
03 -
Add olive oil to a large skillet over medium heat. Add minced garlic and chopped mushroom stems. Cook, stirring frequently, until golden brown, about 5 to 7 minutes.
04 -
Add fresh spinach to the skillet and stir until cooked down and soft, about 4 to 5 minutes. Season with salt and pepper.
05 -
Add cream cheese to the skillet and stir until thoroughly combined with the spinach and mushroom mixture. Remove from heat.
06 -
Gently stir in chopped parsley and all but two tablespoons of grated Parmesan cheese. Stir in Panko breadcrumbs if using.
07 -
Spoon filling into mushroom caps using a little less than a tablespoon of the mixture for each mushroom. Sprinkle the remaining Parmesan cheese on top of the mushrooms.
08 -
Bake for 12 to 15 minutes or until fork tender. Transfer to a serving tray and enjoy hot from the oven.