Preheat the oven to 450°F (230°C).
Take the larger dough ball and place it onto a floured surface. Stretch it with your hands or a rolling pin to form a circle.
Grease a 10-inch pizza pan or oven-safe skillet and spread the dough onto it, ensuring it covers the edges.
Add the mozzarella cheese and spread it evenly on the pizza dough.
Take the smaller dough ball and use a rolling pin to create a second pizza dough circle.
Cover the cheese filling with the topping dough, pressing the edges against the base dough with your fingers.
Prick the topping dough with a fork to prevent it from puffing up during baking.
In a medium bowl, mix the onions with oregano and crushed red pepper flakes.
Spread the onion mixture over the dough.
Add grated Parmesan cheese over the onions.
Place the fugazzeta on the oven floor for about 15 minutes. The aim here is to cook the base of the dough. Then, move the pizza to a middle rack for another 20 minutes. Finally, move it to the top rack for about 5 minutes to brown the onion and cheese topping. Be careful not to burn it, as the timing will depend on your oven type.
Brush the top of the pizza with the prepared pizza chimichurri sauce.
Serve and enjoy!