- Preheat oven to broil setting or high heat. Move oven shelf to the center of the oven.
- Clean mushrooms and remove stems. Combine oil, garlic, and 4 teaspoons of seasoning together in a small bowl. Brush the outside of each mushroom with the oil mixture and place each mushroom, oil side down, on a lightly greased baking sheet.
- Fill each mushroom with 2 tablespoons of pizza sauce, 1/4 cup of mozzarella cheese, pepperoni, and tomato slices. Broil for 8-10 minutes, until cheese has melted.
- To serve, sprinkle with salt, pepper, and the remaining Italian seasoning.