Cut the chicken breast into bite-sized pieces.
Slice the onion and bell pepper thinly.
Boil spaghetti noodles in boiling water.
Heat olive oil in a pan and cook the chicken breast.
When the chicken is partially cooked, add the onion and bell pepper, and stir-fry.
Add the boiled spaghetti noodles to the pan and pour in ketchup.
Season with salt and pepper.
Stir and mix all ingredients well together.
Transfer to a plate.
Generously top with mozzarella cheese (80g).