For a hearty vegetarian polenta casserole, we turned to meaty-tasting mushrooms, which we sautéed until all their liquid evaporated and they were well browned. Garlic and thyme added depth of flavor, and simmering tomatoes with the mushrooms ensured we didn’t lose any of the flavorful fond developed while cooking the mushrooms. To bulk up this dish and add a bright vegetal flavor, we used Swiss chard, which we cooked briefly in the skillet to take away its raw bite, counting on the oven to cook the chard the rest of the way. Sprinkled with flavorful fontina cheese to finish, this casserole made a satisfying vegetarian main course.
Ingredients
- 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
- 4 ounces fontina cheese, shredded (1 cup)
How to Make It
- 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.
- 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 set up slightly while preparing topping.
- Adjust oven rack to middle position and heat oven to 400 degrees. 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.
- 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. Spread mushroom mixture evenly over polenta.
- Sprinkle fontina evenly over top. Bake until hot throughout and cheese is melted, about 20 minutes. Let cool for 5 minutes. Serve.
