Preheat oven to 400℉
Peel and thinly slice your potatoes on a mandoline or as I do in my food processor with the slicing attachment (about 1/8-inch-thick slices). Cover and set aside.
Cut chicken into bite sized pieces
Melt 1/2 cup of butter in a large skillet. Add chicken, stir and cook about 3 minutes. Transfer to a plate with a slotted spoon, cover and set aside.
Add onions to the butter in the skillet and sauté about 4 minutes. Add garlic and sauté for one more minute.
Stir in potato flour, cooking for a few minutes until it forms a pale paste (this is referred to as the roux). The roux will be the thickener for your sauce.
Add chicken stock and stir.
Add chicken, carrots and mushrooms, salt and a few dashes of pepper.
Simmer for 20 minutes while gravy thickens.
Then add coconut milk and stir to combine.
Transfer creamy chicken mixture to a 9 x 13 baking dish.
Arrange potato slices on top overlapping as you go.
Dot with 2 tablespoons of butter.
Cover and bake for 45 minutes. Uncover and bake 20-30 minutes more until top is browned. Let stand for 10 minutes before serving.