How combining earthy lentils, umami-rich mushrooms, and perfectly creamy potatoes creates a plant-based comfort food that will have everyone asking for seconds
Author:Amanda MacArthur
Prep Time:15 min
Cook Time:1h 15 min
Total Time:1h 30 min
Yield:12 servings 1x
Category:Entrées
Ingredients
Scale
Topping:
2½ pounds russet potatoes, peeled and cut into 1-inch chunks
6 tablespoons unsalted butter, melted
½ cup whole milk, warmed
½ cup sour cream at room temperature
½ cup freshly grated Parmesan cheese
Salt and freshly ground black pepper to taste
Filling:
1 cup French lentils, rinsed and sorted
4 sprigs fresh thyme
3½ cups rich vegetable stock
12 ounces mixed mushrooms (shiitake, cremini, and button), sliced
2 large leeks, white and light green parts only, cleaned and thinly sliced
2 medium carrots, diced into ¼-inch pieces
3 cloves garlic, finely minced
2 tablespoons tomato paste
2 tablespoons all-purpose flour
1 cup fresh or frozen peas
1–2 teaspoons fresh lemon juice
Salt and freshly ground black pepper to taste
Instructions
Start by placing your potato chunks in cold, generously salted water. This allows them to cook evenly from the inside out. Bring to a boil and cook until a knife slides through easily, about 15-20 minutes. The key here is to avoid overcooking – you want them tender but not waterlogged.
While the potatoes cook, begin simmering your lentils with thyme and 2 cups of the vegetable stock. Here’s where patience pays off – cook them until just tender but still holding their shape, about 20-25 minutes. They’ll continue cooking later in the sauce, so it’s better to err on the side of slightly firm.
In a large oven-safe skillet (if you have one), melt 4 tablespoons of butter over medium-high heat. Add your mushrooms in a single layer – crowding leads to steaming instead of browning. Let them develop a golden crust before stirring, about 3-4 minutes per side. This caramelization creates those complex umami flavors we’re after.
Reduce heat to medium and add your leeks and carrots to the mushrooms. Cook until the leeks are silky and starting to caramelize at the edges, about 8-10 minutes. Add garlic and cook until fragrant, about 1 minute. The vegetable mixture should be deeply golden and aromatic.
Stir in tomato paste and cook for 2-3 minutes to caramelize it slightly – this adds depth and removes any raw tomato flavor. Sprinkle flour over the vegetables and cook for another minute, stirring constantly. Gradually add remaining stock, stirring constantly to prevent lumps. Add cooked lentils and peas, simmering until the sauce thickens to a rich gravy consistency.
Drain your potatoes thoroughly and return them to the hot pot. This helps evaporate any excess moisture for fluffier mashed potatoes. Add the warm milk-butter mixture and sour cream, mashing until smooth but being careful not to overwork them. Fold in Parmesan, salt, and pepper to taste.
Preheat your oven to 375°F (190°C). Spread the potato topping over your filling. Sprinkle with additional Parmesan if desired.
Bake for 25-30 minutes, or until the potatoes are golden brown and the filling is bubbling around the edges. Let rest for 15 minutes before serving – this allows the filling to set slightly and makes serving easier.
Notes
Room temperature dairy ingredients are crucial for the creamiest mashed potatoes
Don’t skip the resting time – it makes the difference between a sloppy and a perfectly sliceable pie
If making ahead, you can refrigerate the assembled pie for up to 24 hours before baking. Just add an extra 10-15 minutes to the baking time
