It’s important to keep topped up with vitamin D in the darker months because you’re getting less of this bone-strengthening nutrient from its main source: sunlight. This wholesome dish for four from Nicola Graimes and Cathy Seward’s new book, Superfood Slow Cooker (£14.99, Ryland, Peters and Small) features vitamin D-packed porcini mushrooms.

Autumn Porcini and Chestnut Soup

Put around 9g of dried porcini in a bowl, cover with 100ml of just-boiled water and soak for 20 mins. Drain, reserving the liquid, and finely chop the mushrooms. Put them, the liquid, plus 2 chopped onions, 1 thinly sliced celery stick, 2 large chopped garlic cloves, 2 bay leaves, 300g peeled and cubed potatoes, 200g chopped, cooked whole chestnuts, and 2tsp dried thyme into a slow cooker. Crumble in a porcini stock cube and 850ml hot water. Cover and cook on low for 5-6 hours. Remove the bay leaves and blend. Stir in 3tbsp crême fraîche and seasoning. Sprinkle with powder made from grinding 16g dried porcini, 70g crumbled goat’s cheese, and pumpkin seeds.