Peel and cut the potatoes. Cover them with water in a medium saucepan and heat to boiling on high heat. Turn down the heat to medium and cook until they are soft but not soggy. This will take about 15 to 20 minutes.
While the potatoes are cooking, gather the ingredients for your meat layer.
Heat the 2 teaspoons of oil over medium-high heat in a skillet. Add the onion and 1/2 teaspoon of salt. Cook until the onions are golden, about 8 minutes. Turn down the heat to medium after 4 minutes. If the onions are sticking, stir in a tablespoon of water.
Add the ginger garlic paste to the onions, stir for 1 to 2 minutes until it no longer smells raw. Stir in the cinnamon, cardamom, cloves, chili powder, pepper, and the remaining 1/2 teaspoon of salt. Stir, cooking the spices for a minute.
Add the ground turkey. Mash it into crumbles roughly 1/2-inch in size. Stirring occasionally for about 7 to 9 minutes or until the ground turkey is completely cooked. If you mash the ground turkey into tiny crumbles your filling will be too mushy. You want some texture.
Cook the mixture for 3 minutes, then add the tomato sauce. When the mixture is bubbling, turn the heat to medium-low and allow the spices to flavor the meat and the tomato to lose their rawness. Cook for 10 more minutes, stirring several times.
If you haven't already, check on the potatoes for doneness, drain and set aside.
The final sauce should be moist and saucy but not soupy. If you need more liquid, add some stock or water. I often need to add another 2 to 3 tablespoons. Taste for salt, pepper, or chili pepper to your taste. Stir in any vegetables you are using.
Preheat the oven to 400°F (200°C). Finish the potatoes: While they are still warm, mash the potatoes using a fork, potato masher, or hand mixer. Add the butter, dairy, salt, pepper, and cheese (if using).
Stir in a bit more liquid into the mashed potatoes if the mixture is too stiff. But keep it on the thick side so that any patterns you make on the top keep their shape while baking.
Assemble
Layer the meat and tomato mixture into the baking pan.
Dollop big spoonfuls of the mashed potatoes onto the top of the meat and spread out evenly beginning with the edges. This helps seal the juices from bubbling up over the potatoes.
Decorate the smoothed top as the spirit moves you, using a fork or make some fun swirls. If using, brush the top with melted butter and grated parmesan. This helps with browning and gives a nice crisper topping.
Bake for 25 minutes or until hot, bubbly, and the potatoes are golden brown. Test by using a metal utensil—a knife or fork handle—inserting it into the center of the pie. The shepherd's pie is ready when the knife is hot to the touch.
If you want a browner top, increase the oven temperature to broil for the last 5 minutes or so of the heating.
Remove the pie from the oven and allow it to rest on a cooling rack for 10 minutes before serving.
Notes
Ground turkey: I use 93% ground turkey. I have found that ground turkey breast meat is too dry, but you do you.
Heat and chilis: This recipe give you a mildly spiced shepherd's pie. Kashmiri chili has little heat. If you want more heat, add a minced green chili with the ginger and garlic. And use a hotter ground chili or more Kashmiri chili. If you want a mild dish and don't have Kashmiri chili, substitute 1/4 to 1/2 teaspoons of cayenne. You can always add more at the end.
If you are looking for lower glycemic vegetables to swap for the mashed potato layer, consider mashed butternut squash or cauliflower.
Other vegetable ideas: Add mushrooms, sweet potato cubes, celeriac, fennel, turnips, bell peppers, or small pieces of cauliflower to the meat mixture to up the vegetable quotient. Make sure the vegetables are cooked through since the baking step only reheats the dish.
Instead of mozzarella cheese for the mashed potatoes, you might use goat cheese, feta, gruyere, or cheddar cheese. Since all of these cheese are more flavorful, you might start with 1/2 a cup, taste, then add more if needed.
Please note that the nutritional values do not include the optional ingredients.