Cottage pie and lasagne are so nostalgic and I crave them every time autumn arrives and the dark evenings roll in. If you love rich a ragù, potatoes, cheese and creamy sauces, you're going to absolutely love this!! It's the perfect meal prep meal too.
Start off by heating the olive oil in a large saucepan. Add the onion, carrot and celery. Cook with a pinch of salt to soften, about 5 minutes. Once softened, remove and add the mushrooms to the hot frying pan (without any oil). Allow them to release any moisture until they start to brown. Add a splash more oil and fry for a minute or so until they turn golden brown.
Add the veggies back into the pan with the mushrooms, along with the garlic, sun dried tomatoes, tomato purée and chopped herbs. Fry for another minute until everything is coated and the tomato purée caramelises slightly. Add in the rinsed lentils and stir everything together.
Deglaze the pan with the red wine, and cook off until the harsh alcohol smell has evaporated. Then add the soy sauce, balsamic vinegar and stock. Throw in the bay leaves, stir and cover. Simmer for about 25 minutes. Preheat the oven to 200 degrees/180 fan.
Melt the butter in a frying pan then add the plain flour. Whisk together and cook for about 30 seconds until the colour deepens. Slowly add the oat milk, whisking as you do. Once all the milk has been added, gently cook the béchamel for a minute - it will continue to thicken as it cooks. Season with the mustard, and some salt and pepper to taste.
Grab a oven proof dish and prepare to assemble the pie/lasagne. Start with a base of the ragu, spoon some into the bottom of the dish, followed by a generous amount of the creamy béchamel then the thinly sliced potatoes. Repeat the process, adding some cheese in between on top of the béchamel between the layers. Finish by topping the whole thing with more béchamel and plenty of cheese. Cover with foil and bake for about an hour, until the potatoes have softened.
Remove the foil after an hour and continue to cook for another 20 minutes until all the cheese has melted and is bubbling. Serve immediately.