The final dish came out pretty much exactly as I had planned, but I do admit it was a bit more labor-intensive than I initially anticipated.
Not hard at all—just several steps. It all becomes much easier if you divide the process into two days. I recommend making the filling and the mashed potatoes one or two days in advance, then finish them up the day of the party.
And the BEST part of this is you can make a huge batch of these as they keep incredibly well and can be for easy lunches and dinners all week! Multiply the recipe below and you'll be all set!
Stuffed Shepherd's Pie Potatoes
Makes 12, multiply as necessary
For the filling:
2 tablespoons butter
2 large yellow onions, diced
3 large carrots, diced
2 stalks celery, diced
3 garlic cloves, minced
2 pounds ground lamb (substitute all or part ground beef if you'd like)
Kosher salt and black pepper
2 tablespoons all purpose flour
1 1/2 cups beef stock
1 tablespoon brown sugar
1 tablespoon Worcestershire sauce
2 sprigs fresh rosemary
1 cup frozen peas
1/3 cup coarsely chopped fresh parsley
For the mashed potatoes:
3 pounds Yukon Gold potatoes, peeled
1 cup whole milk
1/2 cup heavy cream
1/2 cup (1 stick) unsalted butter
To complete the dish:
12 Idaho potatoes
1/2 grated cheddar cheese
Prepare the filling:
In a large Dutch oven or heavy pot over medium heat, melt the butter. Add the onions, carrots, and celery and sautee for 5 minutes, until the onions are transluscent. Add the garlic and lamb and cook until all the meat is browned. Season with kosher salt and black pepper, then sprinkle with the flour and stir to coat. Pour int the beef stock, brown sugar, Worcestershire sauce and add the fresh rosemary. Bring to a boil, then reduce to low, cover, and let cook for about 15 minutes until sauce thickens. Remove the rosemary sprigs and stir in the frozen peas and fresh parsley. Season to taste with kosher salt and pepper. Then remove from heat and let cool completely (can be chilled in fridge overnight).
Prepare the mashed potatoes: Cut potatoes into large chunks and combine in a large pot of salted water. Bring to a boil then lower heat and let cook for about 15 minutes, or until the potatoes are completely tender. Turn off heat, drain immediately, then return potatoes to the pot to rest for 10 minutes (this will help them dry out a bit). Use a potato ricer or masher to mash the potatoes right in the pot. Add the milk, cream, and butter, and continue to stir and mash until completely smooth. Season to taste with salt and black pepper, then let cool completely (can be chilled in fridge overnight).
The day you are serving:
Preheat oven to 350 degrees. Wash the Idaho potatoes and then use a knife to slice off about 1/4 of the potato lengthwise--almost like removing a lid. Coat lightly with vegetable or olive oil and arrange in a baking dish, cut side up. Bake about 1 hour, or until potatoes are tender. Remove from oven and let cool slightly, then use a spoon to scoop out potato centers to make a hollow potato with thick sides. (Reserve leftover potato for other dishes.)
Fill each potato to the top with the lamb filling. Top with a generous layer of the mashed potatoes on top. Arrange in baking dish again. Sprinkle with cheese and drizzle with olive oil. Return to oven and bake for 25 minutes, until filling is hot and potatoes are heated through and golden on top (you can also turn on the broiler for the last few minutes to create the golden crust.)