Preheat oven to 375 degrees F (190 degrees C).
Heat the olive oil in a large skillet over medium heat. Add the chicken and cook until browned on all sides.
Stir in the onion, mushrooms, salt, and pepper. Cook until the onions ar softened, about 5 minutes.
Add the wine or water and chicken broth. Bring to a boil, then reduce heat and simmer for 5 minutes.
Stir in the parsley.
(Option to add 1/2 cup of a garlic sauce for a creamier base. You can also use a coconut milk instesd.)
Place the potatoes in a single layer in a greased 9x13 inch baking dish.
Bake potatoes for 20-30 minutes, or until the potatoes are tender and slightly browned.
Pour the chicken mixture over the potatoes.
Top with Gruyère cheese.
Bake for another 10 minutes to make sure the potatoes are fully cooked and tender and cheese is melted.