Preheat your oven to 450 degrees f. and line a large sheet pan with parchment paper.
Wipe the mushrooms with a damp paper towel or a mushroom brush and remove the stems. Place your prepared mushrooms onto the sheet pan. Season with sea salt and pepper, to taste.
Fill each with a spoonful of pizza sauce, grated cheese, and a few mini pepperoni as desired.
Sprinkle with oregano.
Bake for 15-18 minutes, or until the cheese is melted and mushrooms are tender.
Garnish with chili flakes and freshly chopped parsley.
Enjoy!