Rustic Vegan Pie

Method

• Peel and finely dice the onion, then finely dice the carrot and celery. Warm the olive oil in a deep sided casserole over a low to moderate heat, then add the vegetables and cook for about 15 minutes until the onion is translucent. Don’t let them brown.
• Peel and thinly slice the garlic, then stir into the softening aromatics.
• Finely chop the thyme and rosemary leaves and with the bay leaves add to the pan.
• Cut the mushrooms into quarters and add, cook for 5 minutes.
• Stir in the cannellini beans with the can water and the vegetable stock and bring to the boil.
• Season with plenty of salt and black pepper then lower the heat and leave to simmer for a good 20-25 minutes.
• If there seems too much liquid (you should have good thick sauce rather than soup) turn up the heat and let it reduce until it thickens.
• Wash and roughly chop the cavolo nero or spinach leaves. Put them and a couple of tablespoons of water into a pan with a tightly fitting lid, then leave over a high heat for a couple of minutes, until the leaves have brightened and relaxed. Drain them, then stir into the sauce and set aside.
• Peel the sweet potatoes, cut them into large pieces and cook them in a steamer basket or colander over boiling water for about 15-20 minutes until soft enough to crush.
• Remove and cut them into thick slices (about 1cm thick).
• Set the oven at 200C/gas mark 6. Transfer the bean filling to a baking dish, ideally a 22cm casserole dish, but a roasting tin will work.
• Place the slices of sweet potato on top of the stew, then brush with olive oil and season with a little black pepper.

Bake for 30 minutes to an hour, until the edges are bubbling.