01 -
In a large bowl, gently combine ground beef, Italian sausage, and pizza seasoning with your hands or a fork until just incorporated. Shape into 4 uniform patties, making each slightly larger than the buns to allow for shrinkage. Press a shallow indent in the center of each patty.
02 -
Preheat a grill or skillet to medium-high heat. Place patties on the hot surface and cook for 4 minutes undisturbed. Flip and continue cooking for 2 to 4 minutes, depending on desired doneness. In the last minute, top each patty with mozzarella slices and cover to allow the cheese to melt.
03 -
While the patties cook, warm marinara sauce in a small saucepan over low heat until hot. Arrange pepperoni slices on a grill-safe pan or foil and heat on the grill or in a dry skillet for 1 to 2 minutes until the edges become slightly crispy.
04 -
Spread butter on the cut sides of the hamburger buns. Place buns, cut side down, onto the grill or hot skillet and toast for 1 to 2 minutes until golden brown and lightly crisped.
05 -
Set each cheesy patty on the bottom half of a toasted bun. Spoon a generous amount of warmed marinara over the patty, top with crisped pepperoni, and sprinkle with Parmesan. Cap with the top bun and serve immediately while hot.