Rustic Polenta Casserole with Mushrooms and Swiss Chard

SERVES 6 TO 8 • TO PREP 1½ HOURS • STORE UP TO 24 HOURS • TO FINISH 1 HOUR 10 MINUTES

WHY THIS RECIPE WORKS: For a vegetarian version of our polenta casserole, we substituted hearty sliced mushrooms for the sausage. To bring out the mushrooms’ flavor, we sautéed them until all their liquid evaporated and they began to brown. Garlic and thyme added depth of flavor to our sauce. To bulk up this dish, we replaced the spinach with heartier Swiss chard, which we cooked briefly to take away its raw bite before cooling the mixture. This ensured that the chard was perfectly cooked when the reheated casserole emerged from the oven. Since the chard continues to cook in the oven during reheating, we found that it was important to reduce all the liquid from our ragu first, so the extra moisture from the chard didn’t turn our sauce watery. Sprinkled with flavorful fontina cheese, this combination of creamy polenta, meaty mushrooms, tomatoes, and Swiss chard was every bit as satisfying as our sausage version.

5

cups water

1⅓

cups whole milk

Salt and pepper

1

cup coarse-ground polenta

2

ounces Parmesan cheese, grated (1 cup)

3

tablespoons unsalted butter

3

tablespoons extra-virgin olive oil

1

onion, chopped fine

1

pound white mushrooms, trimmed and sliced

3

garlic cloves, minced

1

tablespoon minced fresh thyme or 1 teaspoon dried

1

(28-ounce) can diced tomatoes

8

ounces Swiss chard, stemmed and cut into 1-inch pieces

TO FINISH AND SERVE

4

ounces fontina cheese, shredded (1 cup)

TO PREP

1. Bring water and milk to boil in large saucepan over medium-high heat. Stir in 1 teaspoon salt, then very slowly pour polenta into boiling liquid while stirring constantly in circular motion with wooden spoon. Reduce to gentle simmer, cover partially, and cook, stirring often and making sure to scrape bottom and sides of pot clean, until polenta no longer has raw cornmeal taste, all liquid has been absorbed, and mixture has uniformly smooth but very loose consistency, 15 to 20 minutes.

2. Off heat, stir in Parmesan and butter and season with salt and pepper to taste. Pour polenta into 13 by 9-inch baking dish and let cool to room temperature, about 30 minutes.

3. Meanwhile, heat oil in 12-inch skillet over medium heat until shimmering. Add onion and ½ teaspoon salt and cook until softened, about 5 minutes. Add mushrooms and cook until mushrooms have released their liquid and are well browned, about 15 minutes. Stir in garlic and thyme and cook until fragrant, about 30 seconds.

4. Stir in tomatoes and their juice, bring to simmer, and cook, stirring occasionally, until sauce has thickened, about 10 minutes. Stir in chard, 1 handful at a time, and cook until wilted, 2 to 4 minutes. Season with salt and pepper to taste. Let cool to room temperature, about 30 minutes. Spread cooled mushroom mixture evenly over cooled polenta.

TO STORE

5. Wrap dish tightly with plastic wrap and refrigerate for up 24 hours.

TO FINISH AND SERVE

6. Adjust oven rack to middle position and heat oven to 400 degrees. Unwrap dish and cover tightly with greased aluminum foil. Bake casserole until hot throughout and bubbling around edges, about 30 minutes. Remove foil, sprinkle with fontina, and bake, uncovered, until cheese is melted, 10 to 15 minutes. Let cool for 10 minutes. Serve.