In a large skillet, heat the oil over medium-high heat. Add the ground lamb and cook for 7-8 minutes, stirring occasionally, until the meat is cooked through.
Add the diced onion and minced garlic and cook for an additional 2-3 minutes.
Stir in the tomato paste, herbs, paprika, garlic powder, onion powder, cumin, salt, pepper, and red pepper flakes (if using). Cook for 1-2 minutes more, stirring constantly.
Add the cubed sweet potatoes and water. Simmer for 10 minutes, stirring occasionally.
Stir in the frozen peas and cook for an additional 2-3 minutes.
Transfer the mixture to a 9×13-inch (23×33 cm) baking dish. Sprinkle with the chopped parsley.
Bake in the preheated oven for 25-30 minutes, until the top is golden brown.
Serve warm.
Interesting Facts
Shepherd's Pie is a traditional British dish that originated in the 1700s.
The dish is named after the shepherds who often made the dish with whatever ingredients they had on hand.
The dish is traditionally made with ground beef or lamb, but other meats such as chicken or turkey can be substituted.
Sweet potatoes are a great addition to this dish, as they provide a delicious sweetness that balances the savory flavors of the ground meat and herbs.