Brown the BeefIn a large skillet, brown the ground beef over medium heat until fully cooked. Drain excess fat and set aside.
Cook the VegetablesIn the same skillet, heat olive oil over medium-low heat. Add diced sweet potatoes, onion, and carrots. Cover and cook, stirring occasionally, until fork-tender, about 12–15 minutes.Add mushrooms and cook until softened, about 5 minutes.
Make the FillingSprinkle flour evenly over the vegetables and stir to coat. Stir in ketchup.Cook for 1–2 minutes, stirring constantly. Add cream, then pour in the beef broth, red wine (or grape juice), Worcestershire sauce, and thyme.Simmer until thick but still saucy, about 8–10 minutes. Stir the cooked ground beef back into the mixture.Transfer filling to a 1½–2 quart casserole dish.
Make the Potato ToppingPlace cubed potatoes and sweet potatoes in a saucepan and cover with water. Add ½ teaspoon salt.Bring to a boil, then reduce heat and simmer until tender, 15–20 minutes. Drain.Mash with butter and cream until smooth or slightly textured. Season with salt and pepper.
Assemble the PieSpread the mashed potatoes evenly over the beef filling.Optional: brush with egg wash and drag a fork across the top to create ridges.Cut a small vent in the center to prevent overflow.
BakeBake at 375°F (190°C) for 20–30 minutes until hot and bubbling.Broil 2–4 minutes until the top is golden brown.Let rest 10 minutes before serving.
Notes
Use 85–90% lean ground beef for the best flavor.
Sweet potatoes add natural sweetness and replace traditional peas.
Let the filling simmer until thick before assembling to prevent a watery pie.
Fork ridges help the topping brown beautifully under the broiler.