Heat olive oil in a skillet over medium heat.
Add chopped onion and cook until translucent.
Add ground beef, breaking it up during cooking.
Season with garlic powder, Italian seasoning, salt, and black pepper.
Drain any excess fat after cooking.
Prepare the crust:
Place the mini buns (or English muffins) cut-side up on a baking sheet.
Lightly toast them in the oven for 5 minutes to prevent them from becoming soggy.
Assemble the mini pizza burgers:
Spread pizza sauce on each bun.
Add a layer of cooked beef.
Place a tomato slice on top.
Sprinkle mozzarella and Parmesan cheese generously on top.
Sprinkle a pinch of Italian seasoning on top.
Bake:
Place the sheet pan in the oven and bake for 10–12 minutes, or until the cheese is bubbling and golden brown.
Serve and enjoy:
Let cool for one minute before serving.
Optionally sprinkle red pepper flakes on top for extra spice.