Kohlrabi and spinach gratin
- 1 tbsp sunflower oil
- 1 knob butter, plus a little more for greasing the dish
- 2 medium onions (about 600g), halved and finely sliced
- Salt and freshly ground black pepper
- 500g kohlrabi, peeled and cut into 3mm thick rounds
- 250g potatoes, peeled and cut into 3mm rounds
- 2 tsp thyme leaves, chopped
- 200ml double cream
- 200ml water (or chicken or vegetable stock)
- 1 big handful baby spinach, or spinach mixed with kohlrabi leaves
- 1 tbsp parsley, chopped
For the topping
- 60g fresh breadcrumbs
- 25g butter, melted
- 45g cheddar or hard goat's cheese, grated
- Preheat the oven to 190C/375F/gas mark 5. Place a medium-sized frying pan over a medium heat. Add the oil and butter, wait until it foams, then add the sliced onion and a pinch of salt, and sauté for 12 minutes, until soft and starting to take on a little colour.
- Throw in the kohlrabi, potatoes and thyme, and season generously with salt and pepper. Cook, tossing the mixture occasionally, for another five minutes.
- Pour over the cream and stock, simmer gently until the liquid is reduced by half, stir in the spinach and parsley, then place in a lightly buttered gratin dish, about 30cm x 20cm x 7cm in size, levelling it out with a spatula as you go. Place the gratin dish on a baking tray.
- Blitz together the breadcrumbs, butter and cheese in a blender, and sprinkle over the top of the filling. Bake the gratin in a hot oven for about 35-40 minutes, until all golden and bubbling.