1. Pre heat the oven to 180 degrees. In a large saucepan add the potatoes and butternut squash, pour in the milk and yoghurt and season well (if the veg isn’t fully covered, fill with boiling water) Bring to the boil then reduce to simmer for 10 mins.

2. Remove the potatoes and butternut squash with a slotted spoon into a large oven proof dish. Whisk in the chopped sage, nutmeg and cornflour into the milk and yoghurt mixture and season a little more. Bring to the boil and simmer until slightly thickened, this should take around 15 mins. Pour the mixture over the potatoes, then scatter the breadcrumbs, yeast extract and cheese on top. Place in the oven for 30-35 mins until golden and bubbling.

3. With 5 mins to go until the gratin is cooked, boil the green beans in salted water for 5 mins until tender. Drain and serve with the gratin!