Preheat the oven to 450°F. If you have a pizza stone, place it on the middle rack and preheat it for 15 minutes.

Use a serrated knife to slice the French bread loaf in half lengthwise. Mix the butter, 3 tablespoons of olive oil, garlic powder, and ½ teaspoon of salt in a small bowl. Spread the butter mixture on the cut sides of the bread then sprinkle with ⅛ cup of Parmesan cheese. Move the bread to a baking sheet or place it on the pizza stone, and bake for 5-7 minutes until lightly toasted.

Mix the crushed tomatoes with the remaining olive oil and kosher salt. Remove the French bread halves from the oven. Spread each half with the crushed tomato sauce then top with heaping amounts of mozzarella cheese and sprinkle with Parmesan cheese. Add the pepperoni slices or your favorite toppings. Sprinkle with more Parmesan and transfer to the oven on a baking sheet or on the pizza stone. Bake for 10-12 minutes or until the cheese is melted and beginning to brown and the pepperoni cups curl. Remove from the oven, slice, and serve with more grated Parmesan, dried oregano, and red pepper flakes.