Sauté the onion on a frying pan, after it's brown, combine the shredded chicken, the tomato and let it sauté.
Add the tomato purée and season with salt and pepper.
Add the cream and place it in a baking dish.
Mash the corn with the milk and the flour.
In a pan, brown the onion with the butter and combine with the corn mixture.
Season with salt and add the parsley.
Mix until creamy.
Place on top of the chicken, cover with parmesan cheese and bring to a preheated oven (350 °F for 15 min).