Step 1
Preheat the oven to 200C/400F/Gas 6. For the mash potato topping, heat a pan of salted water, add the potatoes and bring to a boil, then simmer until the potatoes are almost cooked through, which is for about 15-20 minutes. Drain and set aside.
Step 2
For the lentil mixture, gently fry the chopped onion, garlic, carrots and celery in a frying pan on a medium heat for 5-10 minutes, until softened.
Add the remaining lentil mixture ingredients (including the vegetarian mince, if using) except for the lentils and season with salt and freshly ground black pepper to taste. Bring the mixture to a boil then reduce the heat and simmer for 10 minutes until the sauce has reduced and the vegetables are tender. Stir the Puy lentils into the sauce.
Step 3
In a small saucepan over a low heat melt the butter, then add the dairy free milk and heat through. Mash the potatoes, then add the warm milk mixture to the potatoes and continue to mash until combined but still chunky. Season with ground black pepper.
Step 4
Tip the lentil mixture into a medium pie dish and top with the mash potato. Add the grated vegan cheese over the top. Then bake in the oven for 25-30 minutes, or until the potato is golden-brown.