Chop the onion into dices and set aside.
In a pan over medium-low heat, place the butter and stir until melted, add the onion and stir well, add the garlic, stir until golden.
Add the ground beef, cook it until it starts to release water, cover the pan and let it cook until the water evaporates.
Cut the tomato into dices, chop the chives and parsley, set aside.
Add the tomato to the meat and mix well, season with salt and black pepper, mix well again. Cover the pan again and cook for 5 to 10 minutes.
Add the parsley and chives, mix and set the meat aside in a bowl.
Get the bread and cut off the entire top, remove or press down the inner part and set aside.
Grate the cheese and mix the cheese with the meat, transfer all this meat and cheese mix to the bread, filling it well.
Sprinkle some mozzarella cheese and some oregano on top, but that's totally to taste.
Bake in a preheated oven at 200°C (392°F) for 20 minutes.
Serve.