In a large mixing bowl, place the ground beef, onions, bell peppers, jalapenos, garlic salt, seasoned salt, and parmesan cheese. Combine the ingredients well. (I use my hands to mix) Mix just until combined.
Divide the mixture into 8 even sized balls. Shape and press into patties to fit the buns.
Place 1 slice of the mozzarella cheese onto 4 of the patties. Top each one with another burger patty and press edges together to seal. Lightly press the patties together.
Spray a cast iron skillet or grill pan with no stick cooking spray. Heat over a medium heat. Place the burger patties in the pan, and cook about 5 minutes on each side, to reach temperature of 160-165 degrees F.
Meanwhile, place the pizza sauce in a small pan and heat on low.
Stir together the butter and the garlic powder. Spread mixture of top and bottom of the buns. Toast in a skillet, under the broiler, or on the grill until light golden brown.
Turn the burger patties off and add 1 slice of cheese to each. Then top each with 4 slices of pepperoni, and the banana peppers. Top each with the remaining slices of cheese.
To serve: Place a bun on a serving plate, spoon 1 Tablespoon of pizza sauce on the bottom of bun. Carefully, place the burger patty on the bun, top with additional pizza sauce. Add the top of the bun.