This is by definition what Shepherd's Pie should be: chunks of juicy braised lamb topped with earthy, buttery wild mushrooms and dreamy cauliflower mash
Rehydrate the dried mushrooms per the instructions on the package and then drain well.
With your fingers, tear the leftover lamb into bite size chunks and arrange the meat at the bottom of a baking dish.
Add the cooking liquid and some or all of the vegetables that were at the bottom of the pan to a food processor or blender and process until smooth; pour ¾ cup of that sauce over the meat. If you didn’t have any of that cooking liquid left, you could simply use some bone or meat broth. It won’t be quite as thick, but if you wanted to thicken it up a bit, you could add a couple of tablespoons of tapioca starch to it.
Add 3 to 4 tablespoons of ghee to a heavy skillet (preferably cast iron) set over medium-high heat. When the pan is hot enough, add the mushrooms and sauté them until they turn a beautiful golden color, about 5 minutes.
Arrange the mushrooms on top of the meat.
Steam the cauliflower until fork tender, about 8 to 10 minutes. Transfer to the bowl of your food processor or high speed blender , add ghee, salt, pepper, tapioca starch and coconut flour and process, stopping to scrape the sides as needed, until a smooth and silky consistency is achieved.
Pour the cauliflower mash over the mushrooms and delicately spread it all the way to the edge of your dish.
Put your Shepherd’s Pie in the oven and bake for about 35-40 minutes, or until the top turns slightly golden.
Drizzle with additional extra-virgin olive oil and garnish with chopped fresh herbs if desired and serve.