Preheat the oven to 400 degrees.

Add the olive oil to a 10-inch cast iron or other heat proof skillet over medium high heat. Add the onion and bell pepper; sauté until the onions become translucent and limp, and the bell pepper has softened (3-4 minutes).

Add the mashed potatoes to the skillet and mix with the onions and bell pepper, breaking up the potatoes until they become smooth and fully combined with the vegetables. Add the turkey in mix in.

In a large mixing bowl whisk the eggs together. Add in the half and half, salt, pepper, 3/4 cups of the cheese; whisk to combine.

Spread the skilled mixture to evenly cover the bottom of the skillet. Pour the egg mixture evenly over the vegetable-potato-turkey mixture in the skillet and sprinkle the diced Italian parsley over the top.

Allow the frittata to cook undisturbed over medium heat until the edges are set; 3-4 minutes. Place the frittata in the heated oven and allow it to finish cooking for 10-12 minutes until the liquid is gone and the top is fluffy and lightly browned. Sprinkle on the remaining ¼ cup cheese and allow to melt 1-2 minutes.

Sprinkle on the remaining ¼ cup cheese and allow to melt 1-2 minutes. Remove from oven, cut into 8 wedges and serve immediately. Any leftovers may be stored in the refrigerator and reheated in the microwave or oven.