Preheat your oven to 190°C/170°C(fan)/375°F/Gas 5.
Heat 1 tablespoon Olive oil in a large pan and then add 300 g Chicken breast. Cook for 3 minutes. Add 2 Leek and 2 Garlic clove and cook for a further 5 minutes, stirring regularly.
Whilst the chicken and leek is cooking, make 4 portion Mashed potato.
Take the chicken off the heat and add 250 ml Creme fraiche,80 g Cheddar cheese, 1 teaspoon Dijon mustard and season. Mix well.
Put the chicken and leek mixture into a baking dish.
Top with mashed potato and 40 g Cheddar cheese.
Bake in the oven for 20 minutes.
Notes
You could use a traditional cheese sauce if you wanted.
Feel free to swap the mashed potato topping for a short crust pastry or even puff or filo.
Give the dish a green boost with some spinach, kale or broccoli.
Reduce the calories by using less cheese in the sauce.
You could swap half the chicken for mushrooms to cut down on the meat. If you do this, try using different mushrooms to change up the texture. Chestnut and shiitake work well.