Creating Oven Polenta with Roasted Mushrooms and Thyme is a straightforward process. Follow these steps for a deliciously creamy side dish:

1. Preheat Oven: Begin by preheating your oven to 400°F (200°C).

2. Prepare the Mushrooms: In a mixing bowl, toss the sliced mushrooms with olive oil, thyme, salt, and pepper. Spread them evenly on a parchment-lined baking sheet.

3. Roast the Mushrooms: Place the prepared mushrooms in the oven and roast for about 25 minutes, or until they are golden brown and caramelized.

4. Cook the Polenta: While the mushrooms are roasting, bring the vegetable broth (or water) to a boil in a medium saucepan. Gradually whisk in the cornmeal to prevent lumps.

5. Thicken the Polenta: Reduce the heat to low and cook the polenta for about 15-20 minutes, stirring frequently, until it thickens and pulls away from the sides of the pan.

6. Add Flavor: Stir in the butter and grated Parmesan cheese, mixing well until the cheese melts and is fully incorporated.

7. Combine Ingredients: Once the mushrooms are roasted, fold them gently into the thick polenta mixture.

8. Transfer to Baking Dish: Pour the polenta mixture into a greased baking dish, spreading it evenly across the surface.

9. Bake: Bake in the preheated oven for an additional 10-15 minutes, allowing the top to become slightly crisp.

10. Garnish and Serve: Remove from the oven, garnish with additional thyme sprigs if desired, and serve warm.

Following these steps will yield a delightful dish that is sure to impress.