01 - In a large bowl, combine ground beef, Italian seasoning, garlic powder, salt, and black pepper. Mix gently until evenly incorporated, then shape into 4 equal-sized patties.
02 - Heat olive oil in a skillet or grill pan over medium-high heat. Cook patties for 4-5 minutes per side until fully cooked through and juices run clear.
03 - Preheat the oven broiler to high. Place the bottom halves of the burger buns on a baking sheet. Spread 1 tbsp of pizza sauce evenly on each bun bottom.
04 - Place a cooked patty on each sauced bun bottom. Spoon another tbsp of pizza sauce over each patty, then layer with shredded mozzarella, pepperoni slices, sliced red onion, and bell pepper.
05 - Place the assembled tray under the broiler for 1-2 minutes until the mozzarella is bubbly and fully melted. Watch carefully to prevent burning.
06 - Remove from the oven, garnish with fresh basil leaves and red chili flakes if desired, then cap each with the top bun half. Serve immediately with extra pizza sauce on the side.