Prepare the Ground Beef
In a large skillet, brown the ground beef over medium heat. Drain any excess grease.
Season and Mix
Transfer the cooked beef to a mixing bowl. Add onion, garlic powder, Italian seasoning, salt, and pepper. Stir until well combined.
Layer in the Crockpot
Spread a thin layer of marinara sauce on the bottom of the slow cooker. Add a layer of the seasoned beef mixture.
Sprinkle half of the diced pepperoni on top, followed by a layer of shredded mozzarella.
Repeat the layers until all ingredients are used, finishing with a layer of mozzarella on top.
Cook
Cover and cook on low for 3-4 hours or until everything is heated through and the cheese is melted.
Assemble the Burgers
Toast the buns (optional) and spoon the cheesy pizza burger mixture onto each bun.
Serve
Add optional toppings like olives or mushrooms for extra flavor. Serve warm and enjoy!