Cook the polenta as directed on the package, following the volume amounts of broth that mark to obtain a very creamy texture. Put it with the broth, butter and a pinch of salt and pepper to cook gently in a saucepan, stirring until the butter dissolves. Keep cooking over low heat, stirring from time to time, adding more broth if necessary.
While the polenta is cooking, cut the onion into fine julienne strips and wash the tomatoes, cutting them in half or quarters. If fresh sage is used, wash and dry well. The chestnuts should already be cooked or roasted and peeled. Heat a little oil in a frying pan and cook the onion with a little salt until it becomes transparent, but not toasted.
Add the tomatoes, season and add the sage. If you don’t have it, you can use thyme, rosemary or a mixture of Provencal herbs. Sauté lightly over high heat and add the chestnuts, chopping them a little if they were very large. Skip the set until the chestnuts are slightly toasted.
At the end of the polenta cooking, add half of the blue cheese And let it melt Garnish with freshly grated or ground nutmeg and serve hot, spreading it out on plates. Spread the chestnut ragout and serve with the leftover cheese so that each guest can serve themselves to taste.