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Recipe

Serves

6 1×

Serves 6Prep 25 minCook 1H5 minTotal 1H30 min

Ingredients

  • 2 tablespoons olive oil
  • 1 large onion, finely chopped
  • 2 carrots, diced
  • 2 celery sticks, finely diced
  • 2 garlic cloves, minced
  • 350 g chestnut mushrooms, sliced
  • 2 tablespoons tomato purée
  • 1 teaspoon dried thyme
  • 1 tablespoon plain flour
  • 2 x 400 g cans green or brown lentils, drained and rinsed
  • 350 ml vegetable stock
  • 1 teaspoon soy sauce, optional
  • Salt and freshly ground black pepper
  • 1 kg floury potatoes, peeled and cut into even chunks
  • 40 g butter
  • 100 ml milk, warmed
  • Salt and black pepper

Method

  1. Heat the oven to 200°C (180°C fan). Put the potatoes in a large pan, cover with cold water and add a generous pinch of salt. Bring to the boil, then simmer for 15–20 minutes, until very tender.
  2. While the potatoes cook, heat the olive oil in a large frying pan or saucepan over a medium heat. Add the onion, carrots and celery. Cook for 8–10 minutes, stirring occasionally, until softened.
  3. Stir in the garlic and cook for 30 seconds. Add the mushrooms and cook for 8–10 minutes, stirring now and then, until their released liquid has evaporated and the mushrooms are beginning to brown.
  4. Mix in the tomato purée and thyme. Sprinkle over the flour and stir for 1 minute so it coats the vegetables. Add the lentils, stock and soy sauce, if using. Bring to a gentle simmer and cook uncovered for 12–15 minutes, stirring occasionally, until the filling is thick but still moist. Season with salt and pepper.
  5. Drain the potatoes well and return them to the warm pan. Leave them for a minute so excess steam can escape. Mash with the butter and warmed milk until smooth. Season to taste. Add a little more milk if needed, but keep the mash firm enough to sit on top of the filling.
  6. Spoon the lentil mixture into a medium ovenproof dish and spread it evenly. Add the mash in spoonfuls, then gently spread it to the edges. Use a fork to mark ridges across the top.
  7. Bake for 25–30 minutes, until the filling is bubbling at the edges and the potato is golden. If you want a more deeply browned top, place the dish under a hot grill for a few minutes and watch it closely.
  8. Leave the pie to stand for 5 minutes before serving. Serve with steamed green beans, peas, cabbage or a crisp salad.

Mushroom and Lentil Cottage Pie

Golden mashed potato topping over mushroom and lentil cottage pie, served in a cream ceramic dish

This mushroom and lentil cottage pie layers a rich, savoury vegetable filling beneath golden mashed potato. Browned mushrooms bring depth, while lentils make the filling substantial. It is a vegetarian main for six, suitable for preparing ahead and serving with green vegetables or a simple salad.

What makes this cottage pie work

Cooking the mushrooms until their moisture has evaporated helps keep the filling rich rather than watery. Lentils add texture and absorb the savoury stock, while a spoonful of tomato purée gives the sauce depth. The topping is simple mashed potato, finished with fork marks that turn crisp in the oven.

Use canned lentils for a straightforward weeknight method. Drain and rinse them before adding to the pan. If using dried lentils, cook them separately according to the packet instructions first; the recipe timing below assumes cooked lentils.

Mushrooms, potatoes, lentils and vegetables arranged for cottage pie preparation

Make-ahead notes

The filling can be cooked a day ahead and kept covered in the fridge. Reheat it until steaming hot before transferring it to the baking dish, or assemble the pie cold and allow extra time in the oven. The topping can also be made in advance, though it is easiest to spread while warm and soft.

For a tidy finish, spoon the mash around the edge of the filling first, then fill the centre. This helps seal the pie and limits bubbling over. A fork dragged lightly across the surface creates ridges that brown during baking.

Recipe

JUMP TO RECIPE

Servings

6

Prep time

25 minutes

Cook time

65 minutes

Total time

1 hour 30 minutes

Tips

  • Brown the mushrooms well. They release water as they cook. Wait until that liquid has evaporated before adding the stock.
  • Keep the filling thick. It should hold its shape when spooned into the dish. Simmer it for a few extra minutes if it looks loose.
  • Use floury potatoes. These mash easily and give the topping a soft, fluffy texture.
  • Dry the potatoes after draining. A short rest in the hot pan lets excess moisture evaporate and helps avoid a wet mash.
  • Check the stock and soy sauce. Both can be salty, so season the filling gradually and taste before adding more.
  • Make individual portions. Divide the filling and mash among smaller ovenproof dishes. Reduce the baking time and check that each portion is bubbling hot throughout.
  • Handle leftovers safely. Cool promptly, refrigerate within two hours and reheat until steaming hot throughout. Follow the Food Standards Agency guidance on cooking and reheating food.

Variations

  • Make it vegan: Replace the butter with plant-based butter and use an unsweetened plant milk. Check that the stock and any optional soy sauce are suitable.
  • Add more vegetables: Stir diced red pepper, peas or finely chopped spinach into the filling. Add spinach near the end so it wilts without making the mixture watery.
  • Use fresh herbs: Replace dried thyme with a few sprigs of fresh thyme. Remove any woody stems before assembling the pie.
  • Add a savoury crust: Scatter a little grated mature cheddar over the mash before baking. This makes the dish vegetarian rather than vegan, so check that the cheese suits your needs.
  • Try a mixed topping: Replace up to a third of the potatoes with peeled parsnip or celeriac. Cook until tender and mash with the potatoes.
  • Make it gluten-free: Use a gluten-free plain flour blend to thicken the filling and check the stock and soy sauce labels.

FAQ

Can I make mushroom and lentil cottage pie ahead?
Yes. Prepare the filling and mash, assemble the pie, cover and refrigerate. Bake until piping hot in the centre. If baking straight from the fridge, allow extra time and check that the centre is hot before serving.

Can I freeze it?
The assembled pie can be frozen once cooled. Wrap it securely and freeze it for up to three months for best quality. Defrost in the fridge before baking, or cook from frozen for longer, checking that it is steaming hot throughout.

What kind of lentils are best?
Green or brown lentils hold their shape and give the filling a hearty texture. Canned lentils are convenient; drain and rinse them before use. Red lentils soften more and can make the filling less textured.

Why is my filling watery?
The mushrooms may not have cooked long enough to release and evaporate their moisture, or the filling may not have simmered long enough. Return it to the pan and simmer uncovered until thickened before topping with mash.

What can I serve with cottage pie?
Steamed greens, peas, cabbage or green beans work well. A crisp salad adds freshness alongside the rich filling and soft potato topping.