This hearty recipe feeds 6 very hungry adults or 8 moderately hungry adults; round it out nicely with a simple green salad. While Deb uses all russet potatoes for the topping, I used half parsnips and half potatoes: parsnips have an earthy, slightly sweet flavor that works really well here. As for mushrooms, I used a mix of portobello, cremini and oyster, but using most (or all) cremini will work just fine.
Recipe ever so slightly adapted from: Smitten Kitchen Every Day
Prepare the mushrooms: In a small bowl, combine the dried mushrooms and boiling water. Set aside for 30 minutes (while you continue with the other steps), then drain, reserving the soaking water, and chop the rehydrated mushrooms into small bits. If the soaking water has any sand or grit at the bottom, pour it through a fine-mesh strainer.
Prepare the lid: Place the potatoes and parsnips in a medium pot, and cover them with a couple inches of salted water. Bring to a boil, and then simmer over medium heat for 12-15 minutes, until both are easily pierced in the center with a knife. Drain, scoop into a bowl and mash with a fork or potato masher. Add the butter, salt and pepper and stir. Add the crème fraîche and milk and stir to combine. If the potato mixture is thicker than you’d like and would be difficult to spread, add more milk, 1 tablespoon at a time. Taste and adjust the seasoning as needed.
Heat the oven to 400 F.
Cook the vegetables: In a large pan (4-quart, or an 11-inch deep skillet or braiser) heat the olive oil over medium heat. Add the onion, carrots, pinch of salt and pepper, and sauté until the vegetables begin to brown ever so slightly, about 10 minutes. Add the garlic and cook for 1 minute more. Add the fresh mushrooms, a pinch of salt, fresh thyme, and increase the heat to high, cooking the mushrooms until they brown and soften, releasing their juices, about 5-10 minutes.
Add the sherry and scrape up any stuck bits. Add the tomato paste, and stir to combine. Add the rehydrated mushrooms and their liquid, plus the stock (start with 1/2 cup stock and add more if mixture seems to dry). Simmer over medium heat for 10 minutes, or until mushrooms are coated in a thick sauce. Taste and season with additional salt and pepper if desired.
Bake the pie: In an oven-safe 2-3 quart baking dish, scoop the mushrooms into an even layer. Top with potato mixture, using the back of your spoon to spread it evenly over the top, all the way to the edges to form a seal. Bake for 25-30 minutes, until lightly browned on top. Garnish with additional thyme and parsley, if desired.
Do ahead: The shepherd’s pot pie keeps for 5 days in the fridge and longer in the freezer. Rewarm in a 350 degree oven for 20 to 25 minutes.
**Note: Deb calls for 1 cup of stock but I found that my mixture really only needed 1/2 cup as the mushrooms released quite a bit of liquid. I’d start conservatively with 1/2 cup and if the mixture needs more, add a little at a time: you want the filling to be saucy but not soupy/overly wet.