Start by boiling the potatoes in a pot of lightly salted water until they are fork-tender. This usually takes around 15 to 20 minutes. Drain the potatoes well before adding sour cream, egg yolk, half and half, and salt and pepper to taste. Mash them until you reach your desired consistency.
While the potatoes are cooking, heat a large skillet over medium heat. Add the ground turkey and onions to the skillet, breaking them apart with a spatula until the turkey is crumbled and browned, which will take about 3 minutes. Look for the turkey to be no longer pink.
Next, add the mushrooms to the skillet. Cook for an additional 5 minutes, stirring occasionally, until the mushrooms are tender and the turkey is cooked through. You should see the mushrooms releasing their juices.
In a separate small skillet, melt butter over medium heat. Whisk in the flour until smooth, creating a roux. Gradually pour in the beef broth and Worcestershire sauce, whisking constantly until the mixture thickens slightly. It should take around 3 minutes.
Pour the gravy mixture into the turkey and mushroom skillet, stirring to combine all the ingredients well. You want to ensure everything is well-coated in the savory gravy.
Add the frozen peas and carrots to the skillet, stirring to incorporate them into the mixture. Cook until heated throughout, which should take about 3 to 5 minutes. You want vibrant colors and a nice warmth.
Transfer the turkey and vegetable mixture to a 2-quart casserole dish. Spread it out evenly, ensuring an even layer for the mashed topping.
Carefully spread the mashed potatoes over the turkey mixture, smoothing it out into an even layer. Be gentle to keep the potato layer light and fluffy.
Sprinkle the top with sweet paprika, which will give it a lovely color and hint of flavor. Then, broil the dish in the oven for 3 to 5 minutes or until the top is lightly golden brown. Keep an eye on it to prevent burning.
Finally, remove the Turkey Mushroom Shepherds Pie from the oven and garnish with parsley. Serve warm and enjoy the comforting flavors!
