Start by folding the sheets of aluminum, shaping them into trays.
Next, transfer these trays to a large baking sheet.
Add the red onions sliced into half-moons, the tomatoes sliced into rounds and set aside.
In a medium bowl, add the olive oil, the soy sauce, the brown sugar, the oregano, the dried rosemary, the salt, a pinch of black pepper, the crushed garlic cloves, mix all the ingredients very well until fully combined and set this sauce aside.
Now, make shallow cuts on the chicken breasts.
Dip the chicken breasts in the seasoning sauce we prepared and place them in the foil trays we made earlier.
Take to a preheated oven at 180° C (350° F) and bake for 40 minutes.
After this time has passed, add the grated mozzarella cheese.
Return everything to the oven until the cheese is completely melted.
Serve.