Preheat oven to 375°F (190°C).
In a bowl, mix beef, breadcrumbs, egg, garlic powder, onion powder, Italian seasoning, salt, and pepper.
Press the beef mixture into a 9-inch pie dish, forming a crust. Bake for 20-25 mins. Drain grease.
Spread marinara sauce over the crust. Sprinkle mozzarella and Parmesan on top.
Add pepperoni, mushrooms, bell peppers, and red pepper flakes as desired.
Bake for another 10-12 mins until cheese melts. Let rest for 5 mins before slicing.