Quick Recipe Version (TL;DR)
Quick Ingredients
- 2 lb (907 g) Yukon Gold potatoes, peeled and cut into 1-inch chunks
- 6 tbsp (85 g) unsalted butter, divided
- 1/2 cup (120 ml) whole milk (or 2%), warmed
- 1 tsp kosher salt, plus more to taste
- 1/2 tsp black pepper, plus more to taste
- 2 tbsp olive oil
- 1 large yellow onion, diced
- 2 medium carrots, diced
- 2 celery stalks, diced
- 12 oz (340 g) cremini mushrooms, finely chopped
- 3 cloves garlic, minced
- 2 tbsp tomato paste
- 2 tsp soy sauce
- 1 tbsp balsamic vinegar
- 1 1/2 tsp dried thyme
- 1/2 tsp smoked paprika
- 1/3 cup (40 g) all-purpose flour
- 2 1/2 cups (600 ml) vegetable broth
- 1 cup (190 g) dried green or brown lentils, rinsed
- 1 cup (150 g) frozen peas
- 1/4 cup (15 g) chopped fresh parsley (optional)
Do This
- 1. Boil potatoes 12–15 minutes; mash with 4 tbsp butter + warm milk, salt, pepper.
- 2. Sauté onion, carrot, celery in oil 8 minutes; add mushrooms and cook until browned, 8–10 minutes.
- 3. Stir in garlic, tomato paste, thyme, paprika; cook 1 minute. Add soy + balsamic.
- 4. Sprinkle flour; cook 1 minute. Slowly whisk in broth.
- 5. Add lentils; simmer covered 25–30 minutes until tender and gravy thick. Stir in peas.
- 6. Spread filling in dish; top with mashed potatoes, rough up, dot with remaining 2 tbsp butter.
- 7. Bake at 400°F (205°C) 18–22 minutes until browned; broil 1–2 minutes if needed. Rest 10 minutes.
Why You’ll Love This Recipe
- Deep, savory flavor from browned mushrooms, tomato paste, and a rich lentil gravy.
- Hearty and classic like traditional cottage pie, but completely vegetarian.
- Simple pantry-friendly ingredients and straightforward steps.
- Great for meal prep: it reheats beautifully and freezes well.
Grocery List
- Produce: Yukon Gold potatoes, yellow onion, carrots, celery, cremini mushrooms, garlic, fresh parsley (optional)
- Dairy: unsalted butter, whole milk (or 2%)
- Pantry: olive oil, tomato paste, soy sauce, balsamic vinegar, dried thyme, smoked paprika, all-purpose flour, vegetable broth, dried green or brown lentils, frozen peas, kosher salt, black pepper
Full Ingredients
For the mashed potato topping
- 2 lb (907 g) Yukon Gold potatoes, peeled and cut into 1-inch (2.5 cm) chunks
- 1 tsp kosher salt, plus more to taste
- 6 tbsp (85 g) unsalted butter, divided (4 tbsp for mash; 2 tbsp for topping)
- 1/2 cup (120 ml) whole milk (or 2%), warmed
- 1/2 tsp freshly ground black pepper, plus more to taste
For the lentil & mushroom filling
- 2 tbsp olive oil
- 1 large yellow onion, diced (about 2 cups / 300 g)
- 2 medium carrots, diced (about 1 cup / 130 g)
- 2 celery stalks, diced (about 1 cup / 120 g)
- 12 oz (340 g) cremini mushrooms, finely chopped
- 3 cloves garlic, minced
- 2 tbsp tomato paste
- 2 tsp soy sauce
- 1 tbsp balsamic vinegar
- 1 1/2 tsp dried thyme
- 1/2 tsp smoked paprika
- 1/3 cup (40 g) all-purpose flour
- 2 1/2 cups (600 ml) vegetable broth
- 1 cup (190 g) dried green or brown lentils, rinsed and drained
- 1 cup (150 g) frozen peas
- 1/4 cup (15 g) chopped fresh parsley (optional, for serving)
- Additional kosher salt and black pepper, to taste
Step-by-Step Instructions
Step 1: Prep and boil the potatoes
Heat the oven to 400°F (205°C). Bring a large pot of water to a boil. Add the potato chunks and 1 tsp kosher salt. Boil until the potatoes are very tender when pierced with a fork, 12–15 minutes.
Drain well, then return the potatoes to the hot pot. Let them sit for 2 minutes to steam off excess moisture (this helps the mash stay fluffy, not watery).
Step 2: Mash the potatoes until creamy
Add 4 tbsp (57 g) butter to the potatoes and mash until mostly smooth. Pour in the warmed milk a little at a time while mashing until creamy and spreadable.
Season with 1/2 tsp black pepper and more salt to taste. Set the mash aside (cover the pot so it stays warm and easy to spread).
Step 3: Build the flavor base with vegetables and mushrooms
In a large, deep skillet or Dutch oven, heat 2 tbsp olive oil over medium-high heat. Add the onion, carrots, and celery. Cook, stirring often, until the onion softens and turns glossy, about 8 minutes.
Add the chopped mushrooms. Cook 8–10 minutes, stirring occasionally, until the mushrooms release their liquid and then begin to brown. This browning step is key for a rich, “meaty” depth of flavor.
Step 4: Add aromatics and seasonings
Stir in the minced garlic and cook for 30 seconds until fragrant. Add the tomato paste, dried thyme, and smoked paprika. Cook for 1 minute, stirring constantly, to caramelize the tomato paste slightly.
Stir in the soy sauce and balsamic vinegar, scraping up any browned bits from the bottom of the pan.
Step 5: Thicken into gravy, then simmer the lentils
Sprinkle the flour over the vegetables and mushrooms. Stir well and cook for 1 minute to remove the raw flour taste.
Slowly pour in the vegetable broth while stirring so the gravy stays smooth. Add the rinsed lentils. Bring to a gentle boil, then reduce heat to a steady simmer.
Cover and simmer until the lentils are tender and the gravy is thick and glossy, 25–30 minutes, stirring every 5 minutes so nothing sticks. If the mixture gets too thick before the lentils are tender, add 1/4 cup (60 ml) water at a time.
Stir in the frozen peas and cook uncovered for 2 minutes. Taste and adjust seasoning with salt and pepper as needed.
Step 6: Assemble the cottage pie
Spoon the hot lentil-mushroom filling into a 9×13-inch (23×33 cm) baking dish and spread into an even layer.
Dollop the mashed potatoes over the top, then gently spread to cover the filling all the way to the edges (this helps seal in the gravy). Use the back of a spoon to create ridges and swirls on the surface; those peaks brown nicely.
Dot the top with the remaining 2 tbsp (28 g) butter, torn into small pieces.
Step 7: Bake until browned and let it rest
Bake at 400°F (205°C) until the filling is bubbling at the edges and the top is lightly browned, 18–22 minutes.
If you want deeper browning, broil on high for 1–2 minutes, watching closely so it doesn’t burn.
Let the pie rest for 10 minutes before serving so the gravy thickens slightly and slices hold together better. Finish with chopped parsley if you like.
Pro Tips
- Chop the mushrooms small: Finely chopped mushrooms blend into the lentils and give a hearty, cohesive texture.
- Brown the mushrooms well: Don’t rush this step; real browning (not just steaming) is where the deep flavor comes from.
- Warm the milk for the mash: Warm milk absorbs more smoothly and helps you avoid gluey potatoes.
- Control the gravy thickness: The filling should be thick but saucy. If it’s thin, simmer uncovered 2–4 minutes; if it’s too thick, loosen with a splash of water or broth.
- Make extra texture on top: The ridges you make with a spoon turn into crispy browned bits in the oven.
Variations
- Extra veg version: Add 1 cup (150 g) diced zucchini or 1 cup (150 g) chopped green beans with the peas.
- Cheesy topping: Stir 1/2 cup (50 g) shredded sharp cheddar into the mashed potatoes, or sprinkle it on top for the last 5 minutes of baking.
- Rustic sweet potato top: Replace half the potatoes with 1 lb (450 g) sweet potatoes for a lightly sweet, golden topping.
Storage & Make-Ahead
Refrigerate: Cool completely, cover tightly, and refrigerate for up to 4 days. Reheat in a 375°F (190°C) oven for 20–25 minutes (covered for the first 15 minutes, then uncovered to re-crisp the top), or microwave individual portions until hot.
Freeze: Wrap the cooled, baked pie tightly (a layer of plastic wrap plus foil) and freeze up to 3 months. Thaw overnight in the fridge, then reheat at 375°F (190°C) for 30–40 minutes until hot in the center.
Make-ahead: Assemble the pie up to 24 hours ahead, cover, and refrigerate. Bake from cold at 400°F (205°C) for 25–30 minutes (it may take a bit longer to heat through).
Nutrition (per serving)
Approximate, based on 6 servings: 430 calories, 14 g protein, 64 g carbohydrates, 14 g fat, 6 g fiber, 650 mg sodium.
