Start by peeling and dicing your potatoes. Place the diced potatoes in a large pot and fill with water to just above the level of the potatoes. Add in the kosher salt. Heat over high heat and boil until potatoes are tender.
Preheat the oven to 350 degrees.
While the potatoes are cooking add the ground turkey to a 12 inch (or larger) cast iron skillet. You will be cooking the pie in this skillet. If you don't have a cast iron skillet you can cook the pie in an 8x8 baking dish. Cook the ground turkey until it is no longer pink and then add in the garlic powder, onion powder, thyme, and salt and pepper. Next add in the flour. Add in a little at a time and stir until the meat is well coated. The amount will vary depending on the moisture level.
Once the meat is well coated with flour add in the chicken stock, milk, and cream. Stir until thick and bubbly. Remove from the heat. Spread into an even layer in the skillet or baking dish.
Now your potatoes should be tender. Drain off the water. Mash the potatoes along with the butter, sour cream, milk, and salt and pepper. Spread mashed potatoes evenly over the meat.
Top with grated cheese. Place in the oven and bake for 20 minutes or until bubbly all around the edges. Let sit at room temp for 15 minutes, if you can, for the gravy to set up.