Cottage pie with butter bean, celeriac and leek mash: Recipe from The Mood Food Manual

From the recipes in The Mood Food Manual that we've been using as part of Tilda's Eat your way to happiness challenge, this is probably one of the ones that takes slightly longer to prepare. But the healthy mash topping is so delicious, you'll never want to go back to regular mash again.

I think it should technically be called a  Shepherd's pie as it is made with lamb but I guess you could use lamb or beef and I'm sure that would taste great too.

Ingredients: 
For the filling:
1 tbsp olive oil
500g minced lamb mince (or soya mince)
1 onion, diced
2 celery sticks, finely chopped
2 carrots, diced
400g tin chopped tomatoes
2 tbsp tomato purée
1 tbsp Worcestershire sauce
1 bay leaf
1 tsp fresh thyme leaves, chopped
300ml gluten free vegetable stock
Salt and freshly ground black pepper

For the topping:
500g celeriac, peeled and cubed
400g tin butter beans, rinsed and drained
100g crème fraîche or natural yoghurt
1 tbsp olive oil
2 leeks, trimmed and cut into 3mm slices
Salt and freshly ground black pepper

Method:

Preheat the oven to 200°C/Gas mark 6. Heat the oil in a large saucepan. Stir in the mince lamb or soya mince and cook for another 1–2 minutes. Add the onion, celery and carrots and allow cook for about 10 minutes, until softened.

Stir in the chopped tomatoes, tomato puree, Worcestershire sauce, bay leaf, thyme leaves and stock. Add salt and pepper and bring to the boil. Cover and simmer for 30 minutes, stirring occasionally.

To make the topping, bring a large saucepan of water to the boil and cook the celeriac until soft, about 8 minutes. Drain well and tip into a large bowl. Add the butter beans and crème fraîche or yogurt and mash until smooth.

Heat the oil in a pan and gently sauté the leeks over a medium heat. Add them to the celeriac and bean mash and season well to taste. Pour the cooked mince mixture into a shallow ovenproof dish and top with mash. Bake in the oven for 20–30 minutes, until the top is golden brown.

Recipe reproduced with kind permission from Tilda. All the recipes can be found in the Tilda 'The Mood Food Manual'.