For the Mushroom Ragù:

In a large pan, heat olive oil over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes.
Add the minced garlic and cook for another minute until fragrant.
Stir in the chopped mushrooms and cook until they release their moisture and become tender, about 8-10 minutes.
Add the cherry tomatoes (or canned tomatoes), red wine (if using), oregano, thyme, salt, and pepper. Simmer for 15-20 minutes until the sauce thickens slightly. Adjust seasoning as needed.
Remove from heat and garnish with fresh parsley.

For the Polenta:

In a saucepan, bring the water or broth to a boil. Add the salt.
Gradually whisk in the cornmeal, stirring constantly to prevent lumps.
Reduce the heat to low and cook, stirring frequently, for about 20-25 minutes until thickened and creamy.
If using, stir in the butter and grated Parmigiano-Reggiano cheese until melted and well combined.
Spoon the polenta onto plates and top with the mushroom ragù. Garnish with additional parsley and serve warm.