Trim the ends off the celery and finely slice it. Finely slice the mushrooms. Warm a deep frying pan or wok over a medium heat for 1 min. Add 1 tbsp oil, the celery and mushrooms. Season.
Turn the heat to low. Fry and stir for 8 mins till
the celery has softened and the mushrooms
have picked up a little colour.
While the veg cook, roughly chop all of the chestnuts. Peel and grate the garlic. Strip the leaves from the rosemary sprigs and finely chop them.
Stir the garlic and most of the rosemary leaves into the pan. Cook and stir for 1 min, then add the chestnuts.
Crumble the stock cube into the frying pan or wok with the mushrooms. Pour in 200ml boiling water. Cover and simmer for 10 mins till the liquid has reduced by half. Stir now and then.
While the mushrooms simmer, pour 500ml boiling water into a high-sided pan over a medium heat. Bring to the boil. Trickle in the polenta, whisking as you go to smoothly combine it with the water. Once it’s all in, turn the heat down low
Cook the polenta for 5 mins, stirring now and then till it's thick, creamy and pulls away from the side of the pan as you stir it. Take off the heat.
Chop the butter into the polenta and stir till it melts. Grate in half the cheddar cheese. Taste and add a little salt and pepper if you think it needs it.
Put the salad leaves in a bowl. Toss with ½ tbsp olive oil and a pinch of salt and pepper.
Spoon the polenta into warm bowls. Top with the chestnut and mushroom sauce and scatter over the last of the rosemary to garnish. Grate over a little more cheddar and serve with the salad leaves.
Feel free to liberally grate the remaining cheddar over the top of your finished dish. Or grate into homemade pastries, sweet or savoury for a tangy cheesey twist.