Ingredients
1 litre/1 pint 15fl oz vegetable stock
1 tbsp chopped rosemary
2 tsp flaky sea salt
250g/9oz instant polenta, sieved
200g/7oz blue cheese
100g/3½oz butter
1 large white onion, sliced
½ Savoy cabbage, core removed and the leaves sliced thinly
salt and freshly ground black pepper
2 tbsp thyme leaves
6 tbsp extra virgin olive oil
300g/10oz large field mushrooms, sliced
4 garlic cloves, chopped
3 tbsp balsamic vinegar
handful coarse breadcrumbs

Method
1. Preheat the oven to 190C/375F/Gas 5.
2. Using a non-toxic pen and a dinner plate as your stencil, draw a circle on each of two sheets of baking parchment and place each piece of parchment on a baking sheet.
3. Bring the vegetable stock to the boil with the rosemary and two teaspoons of flaky sea salt. Slowly pour in the polenta, whisking as you go to prevent lumps forming, until all has been added. Turn the heat down, swap the whisk for a spoon, and continue to stir the polenta as it bubbles away for 3-4 minutes. It will bubble explosively, much like porridge, so be careful.
4. Take the polenta off the heat and stir in the cheese, then spoon half in the middle of each of the baking parchment circles. Using a wet spatula, spread the polenta out to make two identical discs. Leave to cool and firm up.
5. In a wide pan, heat the butter until nut-brown, then add the onion and cook over a high heat, stirring often, to caramelise it. Add the cabbage and thyme and cover with a lid, then cook over moderate heat for 7-10 minutes, stirring every few minutes, to soften the cabbage.
6. Season well with salt and freshly ground black pepper, then tip the cabbage on to one of the polenta discs and place the other disc on top - it may be easier to flip it on. If it breaks, it's no drama, but do try to keep it in one piece - or at least two.
7. Don't wash the pan out, but add four tablespoons of the olive oil to the pan and sauté the mushrooms and garlic until they're just cooked. Add the balsamic vinegar and cook for another minute.
8. Tip the contents of the pan on top of the second disc of polenta, sprinkle with the breadcrumbs and the remaining oil, and bake in the top of the oven until the crumbs are golden.
9. Serve hot, although it can be reheated the following day.