Cut the chicken breast into bite-sized pieces.
Chop the broccoli and onion into edible sizes.
Heat olive oil in a pan and sauté the chicken breast.
Add the onion and broccoli and stir-fry together.
Season with salt and pepper.
Place the sautéed ingredients in an oven-safe dish.
Top with tomato sauce.
Generously sprinkle mozzarella cheese over it.
Bake in a preheated oven at 200°C for 10 minutes.