Preheat the oven to 180°C (350°F). Finely mince the garlic. Dice the onion.
Heat olive oil in a saucepan over medium heat. Add the diced onion and minced garlic, and cook for 5 minutes until translucent.
Add the canned tomatoes. Reduce heat to low and simmer for 2-3 minutes.
Wash and roughly chop the rocket. Add it to the sauce. Season with salt, pepper, and Italian herbs.
Bring the sauce back to a gentle boil, then taste and adjust seasoning as needed. Remove from heat.
Pat the chicken breast fillets dry. Heat olive oil in a separate pan over medium-high heat. Fry the chicken for 5-7 minutes per side until golden on the outside.
Slice the mozzarella into thin slices.
Place the fried chicken in a baking dish. Pour the tomato sauce over it and arrange mozzarella slices on top. Sprinkle with pepper and Italian herbs.
Bake in the preheated oven for 10-15 minutes until the mozzarella is melted and lightly browned, and the chicken is cooked through.