Preheat the oven to 350 degrees.

Place the potato chunks into a large pot and add cold water to cover them. Bring to a boil over high heat, then reduce to medium low and simmer uncovered until the potatoes are fork tender (about 15 minutes).

Drain the potatoes and return to the pan. Smash the potatoes using a hand held mixer or a potato masher. Add the sour cream, butter, milk and salt.

Taste and adjust seasoning. Set the mashed potatoes aside until assembly.

For the filling, heat oil in a 10-12 inch cast iron skillet (or oven safe pan) over medium heat. Add onion, celery, carrot and cook until softened, about 5 minutes.

Add the ground turkey and garlic, and crumble/cook until browned, about 5 minutes.

Stir in the rosemary, ground sage, salt, pepper, onion powder, flour and tomato paste and cook 1 minute.

Deglaze the skillet with the red wine and reduce, about 4-5 minutes.

Stir in the beef broth, frozen peas and Worcestershire and bring to a boil. Simmer filling for 2-3 minutes.

Dollop the mashed potatoes evenly over the filling in the cast iron skillet. Using a spoon or spatula, spread the potatoes evenly over the filling and all the way to the edges of the skillet.

Transfer the skillet to the oven. Bake at 350 degrees for 30 minutes.

You can place under the broiler for 5 minutes at the end if you want the top to be golden brown.

Let the Shepherd’s Pie rest for 5 minutes before serving.