01 - Preheat your oven to 425°F.
02 - On a large baking sheet, toss the mushrooms with olive oil, garlic, thyme, salt, and pepper. Spread in an even layer.
03 - Roast the mushrooms for 20–25 minutes, stirring once halfway through, until golden and tender.
04 - Bring the water or broth to a boil in a medium saucepan. Add salt.
05 - Gradually whisk in the polenta in a steady stream to prevent lumps. Reduce heat to low and cook, stirring frequently, until thick and creamy (about 20–25 minutes).
06 - Stir in butter, milk or cream, and Parmesan cheese until fully incorporated and smooth. Adjust seasoning if needed.
07 - Divide the creamy polenta among bowls or plates. Top with roasted mushrooms and their juices. Garnish with parsley and extra Parmesan, if desired.