Wash the chicken filet and pat dry. Heat the oil in a pan, fry the fillet in it and cook on medium heat for about 10 minutes. In the meantime, grate Gouda and Parmesan cheese. Cut mozzarella into slices.
Clean and wash the spring onion and cut into fine rings. Wash, clean and slice the tomatoes. Take the chicken out of the pan and cut it into slices. Toast the slices of toast. Cover with chicken fillet slices, tomatoes and mozzarella.
Sprinkle with gouda and parmesan. Bake in the preheated grill for about 5 minutes. Sprinkle with spring onion and serve immediately.