Slow Cooker Lentil & Vegetable Cottage Pie is a meat-free version of the classic British cottage pie made with lentils, vegetables and a potato-cauliflower mash topping.
The lentils slowly cook with tomatoes, herbs and broth to create a thick filling that works well so well with the creamy topping.
Building a Deep Base for Lentil Cottage Pie
The first stage of cooking happens in a large skillet rather than the slow cooker. Cooking the onion, celery and carrots in butter or oil helps soften them and begins developing a strong savory base for the filling.
Mushrooms are added next and cooked until their moisture evaporates, if you also brown them slightly it adds even more flavor.
Tomato paste is cooked briefly in the pan before adding liquid. Deglazing the pan with red wine or broth lifts the browned bits (which is all the flavor goodness!) from the pan and carries them into the filling.
Have a slow cooker question? I’ve gathered the most common ones in my Slow Cooker FAQ if you’d like to learn a little more.
How Slow Cooking Changes Lentil Texture
Green or brown lentils work best for this recipe because they hold their shape while becoming very tender during long cooking.
As the lentils cook they absorb broth and tomato juices, which makes them thick and juicy. By the end of cooking they should be soft enough to sit comfortably in a thick sauce rather than feeling separate from it.
Slow cooker timing can vary slightly by model. The filling is ready when the lentils are very tender, you can squash them between your fingers and the mixture looks thick and spoonable.
You may notice the recipe begins with one hour on HIGH before switching to LOW if cooking on the low setting.
This helps bring the slow cooker up to temperature quickly so the lentils begin softening properly. Lentils can sometimes stay firm several hours later if the cooker heats too slowly at the start.
After the initial hour, reducing the heat to LOW allows the filling to cook gently while the lentils finish softening and the sauce thickens.
For a thicker, more hearty result, take a look at my guide How to Thicken Slow Cooker Sauce which explains several simple methods.
Why a Potato and Cauliflower Mash Works Well on Top
Using both potatoes and cauliflower keeps the mash lighter than potatoes alone while still giving a smooth topping. Plus we love a hidden vegetable!
After draining, return the vegetables to the warm pot for a few minutes so excess steam can evaporate, this helps prevent a watery mash.
Mash with butter and sour cream or cream cheese until smooth and spreadable. A small pinch of nutmeg adds gentle warmth. You may not need the extra milk, so just decide as you go.
Spread the mash evenly over the lentil filling and sprinkle with cheese. The cheese helps the topping turn golden and hold together when serving and tastes so good!
How to Make Slow Cooker Lentil & Vegetable Cottage Pie
Full ingredient quantities and detailed instructions are in the recipe card below.
Step 1 – Soften the vegetables
Cook the onion, celery and carrots in a skillet until softened. Add the mushrooms and continue cooking until their moisture has evaporated.
Step 2 – Add the flavor base
Stir in the garlic, paprika and tomato paste, then deglaze the pan with the red wine or broth.
Step 3 – Slow cook the filling
Transfer the mixture to the slow cooker with the lentils, tomatoes, broth and seasonings. Cook until the lentils are very tender and the filling is thick, adding the peas near the end of cooking.
Step 4 – Make the mash topping
Boil the potatoes and cauliflower until soft, then drain well and mash with the butter, dairy and seasoning.
Step 5 – Assemble and bake
Spread the mash over the lentil filling, top with cheese and bake until golden.
More Slow Cooker Vegetarian Recipes
If you enjoyed this Slow Cooker Lentil & Vegetable Cottage Pie, here are a few more slow cooker vegetarian friendly recipes to try.
- Slow Cooker Red Lentil Curry
- Slow Cooker Minestrone Soup
- Slow Cooker Tomato & Basil Soup
- Slow Cooker Pumpkin & Chickpea Curry
These recipes use simple vegetables and pantry ingredients to create slow-cooked meals with minimal preparation.
Slow Cooker Lentil & Vegetable Cottage Pie
A slow cooker lentil and vegetable cottage pie with a thick savoury filling and a creamy potato-cauliflower mash topping baked until golden.
Ingredients
Lentil & Vegetable Filling
- 2 tablespoons butter or olive oil
- 1 onion, finely diced
- 1 celery stalk, finely sliced
- 3 large carrots, cut into ½-inch pieces
- 7 oz mushrooms, sliced
- 1 cup diced pumpkin or butternut squash, peeled and cut into ½-inch cubes
- ½ red bell pepper, diced small
- 1 tablespoon garlic, minced
- ½ teaspoon paprika
- 1/4 teaspoon cumin powder
- 1 tablespoon all-purpose flour
- 2 tablespoons tomato paste
- ½ cup dry red wine (Pinot Noir or Merlot) or vegetable broth
- 1 teaspoon dried thyme
- 1 teaspoon of dried oregano
- 1¼ cups dried lentils (230 grams) green or brown), picked over & rinsed
- 3½ cups vegetable broth
- 1 (14 oz) can diced tomatoes
- 1 bay leaf
- 2 teaspoons Worcestershire sauce (vegan if required)
- 1 teaspoon soy sauce
- 1/2 teaspoon Marmite or Vegemite (optional)
- 1 Tablespoon brown sugar
- 1 teaspoon salt
- ½ teaspoon black pepper
- ¾ cup frozen peas
- 2 teaspoons red wine vinegar or apple cider vinegar
- 1 tablespoon butter (optional, to finish)
- Salt to taste
Mashed Potato & Cauliflower Topping
- 1½ lb Yukon Gold or yellow potatoes, peeled and cut into chunks
- 1 lb cauliflower florets
- Vegetable broth or water to cover
- 2 tablespoons butter
- 3 tablespoons sour cream or cream cheese
- Optional: 3–4 tablespoons milk
- 1 teaspoon salt
- ½ teaspoon black pepper
- Pinch nutmeg
- 1 cup shredded cheese (cheddar works well)
Instructions
Lentil & Vegetable Filling
- Heat a very large skillet over medium heat and add the butter or oil then add the onion, celery and carrots. Cook for about 5 minutes, stirring often, until softened.
- Add the mushrooms and cook for a further 5 minutes until softened and starting to brown. Then add in the pumpkin and bell peppers and cook for a further 3 minutes.
- Stir in the garlic, paprika and cumin and cook for 30 seconds, Sprinkle over the flour and stir to coat the vegetables for 30 seconds, then add the tomato paste, stir and cook for 1–2 minutes.
- Pour over the red wine and allow it to bubble for 2–3 minutes until slightly reduced.
- Transfer the mixture to the slow cooker, scraping all the scrapings and flavor from the bottom of the pan.
- Finally add the rinsed lentils, vegetable broth, diced tomatoes, bay leaf, thyme, oregano, Worcestershire sauce, soy sauce, marmite, brown sugar, salt and pepper. Stir well.
- Cover and cook on HIGH for about 6 hours, or LOW for 8–9 hours.
- If cooking on LOW, begin on HIGH for 1 hour, then reduce to LOW for the remaining time. It is important to cook until the lentils are tender and the filling is thick.
- Stir in the frozen peas during the final 30–45 minutes of cooking.
- Remove the bay leaf. The filling should be thick and spoonable. If it seems too loose, cook uncovered on HIGH for 20–30 minutes to reduce while you prepare the topping.
- Taste the soup at this stagem, to brighten the flavours, add some red wine vinegar or apple cider vinegar. Taste again and add salted if needed, then stir through the knob of butter for extra richness.
Potato & Cauliflower Topping
- Place the potatoes and cauliflower in a large saucepan and cover with salted water or vegetable broth.
- Bring to a boil and cook until very tender.
- Drain well and allow the steam to evaporate by placing the vegetables back into the pot on the turned-off burner for 2–3 minutes.
- Mash with the butter, salt, pepper and a pinch of nutmeg.
- Stir in the sour cream or cream cheese until smooth. Add milk a tablespoon at a time if required.
- Taste and adjust seasoning with additional salt and pepper if needed.
To Finish
- Preheat the oven to 400°F (200°C)
- Spoon the lentil filling into a large oven-safe baking dish (about 9 × 13 inches).
- Spread the mash evenly over the top and sprinkle with the grated cheese.
- Bake for 20–25 minutes until golden and bubbling. Let rest for 5–10 minutes before serving.
- Lovely served with crusty bread or a simple green salad.
Storage:
- Cool completely, then cover and refrigerate for up to 3–4 days, or freeze either before baking or after baking once cooled. Wrap well and freeze for up to 3 months.
- Thaw overnight in the refrigerator if frozen, then reheat in the microwave or a 350°F oven until piping hot and heated through.
Notes
Vegetable variations: Add leeks, diced potatoes, parsnips, fennel or zucchini if you like. Cut root vegetables small so they soften properly. Add softer vegetables like zucchini in the final 1–2 hours.
Using canned lentils: Dried lentils give the best texture. If using canned, reduce the broth by about 1 cup and add the lentils during the final 1–2 hours.
If the filling is too thick: Stir in ¼–½ cup hot broth or water before assembling until the filling loosens slightly.
Make ahead: The lentil filling can be made 1 day ahead and refrigerated. Assemble with fresh mash and bake before serving.
Vegetable size: Cut root vegetables into ½-inch pieces or smaller so they cook at the same rate as the lentils.
Slow cooker tip: If cooking on LOW, start the recipe on HIGH for the first hour. This helps the lentils begin softening and prevents them staying firm.
Nutrition Information:
Yield: 8 Serving Size: 1Amount Per Serving: Calories: 444Total Fat: 21gSaturated Fat: 10gUnsaturated Fat: 11gCholesterol: 48mgSodium: 1409mgCarbohydrates: 48gFiber: 11gSugar: 11gProtein: 18g
This nutrition calculation for Just Slow Cooker Recipes has been automated, please use your discretion with the calculation and use your own if unsure.
Frequently Asked Questions
Can I use canned lentils instead of dried?
Dried lentils work best because they absorb the cooking liquid and help thicken the filling. If using canned lentils, reduce the broth slightly and add them during the final 1–2 hours.
Why start the slow cooker on HIGH first?
Starting on HIGH helps the slow cooker reach temperature quickly so the lentils begin softening properly. After the first hour the heat can be reduced to LOW for the remainder of the cooking time.
What vegetables can I add?
This filling works well with additional vegetables such as leeks, parsnips, fennel or diced potatoes. Cut root vegetables small so they soften during the long cooking time.
I hope you love this!
I hope you love this Slow Cooker Vegetable & Lentil Cottage Pie as much as we do. Comfort food at its best!
If you try it, I’d love to hear how it turned out for you in the comments below.
Also, if you enjoy this recipe, please leave a ⭐ rating in the recipe card above. Your feedback helps other readers and really supports my recipes.
Thank you so much for visiting and taking the time to try this recipe. I hope you find plenty of slow cooker inspiration here on my blog.
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Happy cooking!
Anna
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