This appetizer is very common at any Italian home including my own kitchen. You can add any left over mushrooms into a sauté with chicken or throw in your sauce or breakfast frittata!
Preheat the oven to 400 degrees F.
In a medium bowl, add mushrooms and pour in 2 tablespoons of olive oil. Season with 1 teaspoon sea salt and 1/2 teaspoon pepper, then stir together using a large spoon.
In a small bowl, add in peppers, olives, and scallions. Drizzle 1 tablespoon of olive oil and 1/2 teaspoon sea salt and 1/4 teaspoon pepper, then stir to coat with a spoon.
On a parchment paper-lined baking sheet place the mushrooms, cavity side up. Spoon the filling into each mushrooms cap. Bake until the mushrooms are tender, about 20 minutes.
Transfer the mushrooms to a serving platter, sprinkle with a chopped basil, and serve.