Mushroom Polenta Casserole: A Creamy, Cheesy Delight

This Mushroom Polenta Casserole is the ultimate comfort food, blending earthy, savory mushrooms with a luxuriously creamy and cheesy polenta base. It’s a rustic yet elegant dish that feels like a warm hug on a plate. If you’re searching for a vegetarian meal that is both incredibly satisfying and packed with flavor, you’ve found it. This recipe is perfect for a cozy weeknight dinner but special enough to serve to guests.

We combine a rich mushroom ragout with perfectly cooked, creamy polenta and bake it all to golden, bubbly perfection. It’s a straightforward recipe that delivers restaurant-quality results right in your own kitchen.

Why This Mushroom Polenta Casserole is a Must-Try

This isn’t just another casserole; it’s a culinary experience. The polenta is cooked to a perfect, creamy consistency, creating a soft, comforting bed for the intensely flavorful mushrooms. The ragout, enriched with garlic, herbs, and a touch of white wine, brings a depth of flavor that is simply irresistible. Topped with a generous layer of cheese that melts and browns beautifully in the oven, this dish is a true showstopper.

• Incredibly Flavorful: A rich combination of mixed mushrooms, aromatic herbs, and two types of cheese.
• Hearty and Satisfying: This vegetarian casserole is filling enough to be a main course.
• Perfectly Textured: The contrast between the creamy polenta, tender mushrooms, and cheesy crust is divine.
• Elegant Yet Easy: Simple enough for a weeknight but impressive enough for a dinner party. If you enjoy this, you might also love our Salsa Verde Chicken Casserole (coming soon) for another easy weeknight win.

Ingredients You’ll Need

To make this baked polenta casserole, you’ll need a few simple, high-quality ingredients. The magic is in how they come together.

For the Creamy Polenta

• Yellow Cornmeal (Polenta): The star of the base. Look for medium or coarse-ground for the best texture.
• Vegetable Broth & Milk: Using a combination of both creates a richer, creamier polenta. You can use whole milk or even heavy cream for extra decadence.
• Unsalted Butter: Adds richness and a smooth mouthfeel.
• Parmesan Cheese: Freshly grated Parmesan provides a nutty, salty flavor that seasons the polenta perfectly.
• Salt and Black Pepper: To taste.

For the Savory Mushroom Ragout

• Mixed Mushrooms: A mix of cremini, shiitake, and oyster mushrooms provides a wonderful depth of flavor and texture.
• Olive Oil and Butter: For sautéing the aromatics and mushrooms.
• Yellow Onion & Garlic: The essential flavor base for the ragout.
• Dry White Wine: A splash of something like Sauvignon Blanc or Pinot Grigio deglazes the pan and adds a touch of acidity.
• Fresh Thyme and Rosemary: These herbs are classic pairings for mushrooms and add a wonderful, woodsy aroma.
• Gruyère Cheese: For topping the casserole. Its nutty, slightly sweet flavor melts beautifully and creates a perfect golden crust.

Step-by-Step Instructions

Follow these simple steps to create the most delicious Mushroom Polenta Casserole. We’ll prepare the mushroom ragout first, then the polenta, and finally assemble and bake.

Prepare the Mushroom Ragout

1. Sauté Aromatics: In a large skillet or Dutch oven, heat olive oil and butter over medium heat. Add the chopped onion and cook until softened, about 5-7 minutes. Add the minced garlic and fresh thyme and cook for another minute until fragrant.
2. Cook Mushrooms: Increase the heat to medium-high, add the sliced mushrooms to the skillet. Cook, stirring occasionally, until they release their liquid and begin to brown, about 10-12 minutes. Don’t overcrowd the pan; cook in batches if necessary.
3. Deglaze and Simmer: Pour in the white wine to deglaze the pan, scraping up any browned bits from the bottom. Let it simmer until the wine has almost completely evaporated. Season with salt and pepper, then remove from heat and set aside.

Cook the Polenta

1. Boil Liquids: In a medium saucepan, bring the vegetable broth and milk to a simmer over medium-high heat.
2. Whisk in Polenta: Once simmering, slowly pour in the polenta while whisking continuously to prevent lumps from forming.
3. Simmer and Stir: Reduce the heat to low and continue to cook, stirring frequently with a wooden spoon, until the polenta is thick and creamy, about 20-25 minutes.
4. Add Finishings: Remove the polenta from the heat and stir in the unsalted butter and grated Parmesan cheese until fully melted and incorporated. Season with salt and pepper to taste. For a different cheesy delight, try our white cheddar mac and cheese recipe (coming soon).

Assemble and Bake the Casserole

1. Preheat Oven: Preheat your oven to 375°F (190°C). Lightly grease a 9×13 inch baking dish.
2. Layer Polenta: Spread the creamy polenta evenly into the bottom of the prepared baking dish.
3. Add Mushrooms: Spoon the savory mushroom ragout over the polenta in an even layer.
4. Top with Cheese: Sprinkle the shredded Gruyère cheese evenly over the mushroom layer.
5. Bake: Bake for 20-25 minutes, or until the casserole is heated through and the cheese is melted, bubbly, and lightly golden. For a crispier top, you can place it under the broiler for the last 1-2 minutes, watching carefully to prevent burning.
6. Rest and Serve: Let the casserole rest for 5-10 minutes before serving. This allows it to set up slightly, making it easier to serve. Garnish with fresh parsley if desired.

Tips for the Perfect Baked Polenta

Making a great Mushroom Polenta Casserole is easy, but a few expert tips can elevate it from good to absolutely unforgettable.

• Use Quality Ingredients: Since the ingredient list is simple, using good quality mushrooms, fresh herbs, and real Parmesan cheese makes a huge difference.
• Don’t Stop Stirring: When making the polenta, frequent stirring is key to achieving a creamy, lump-free texture.
• Mushroom Variety is Key: Using a mix of mushrooms like cremini, shiitake, and oyster adds layers of flavor and texture that you can’t get from just one type.
• Let It Rest: Allowing the casserole to rest after baking is crucial. It helps the polenta firm up just enough to be served in clean portions. Much like our famous baked ziti, a little patience pays off.

Variations and Substitutions

This recipe is wonderfully versatile. Feel free to make it your own with these creative variations.

• Add a Protein: Stir in some cooked, shredded chicken, Italian sausage, or even white beans into the mushroom mixture to make it even heartier.
• Make it Vegan: Use a plant-based butter, full-fat oat milk, and vegan Parmesan and Gruyère alternatives. The results are just as creamy and delicious.
• Different Cheeses: Fontina, mozzarella, or a smoked provolone would also be fantastic as a topping instead of or in addition to Gruyère.
• Spice it Up: Add a pinch of red pepper flakes to the mushroom ragout for a gentle touch of heat.

What to Serve with Your Casserole

This Mushroom Polenta Casserole is a complete meal on its own, but it also pairs beautifully with a few simple sides. A crisp green salad with a lemon vinaigrette offers a fresh contrast to the rich casserole. Alternatively, serve it with some roasted asparagus or a side of crispy roasted potatoes for a truly comforting feast.

Storing and Reheating Leftovers

Leftovers are just as delicious the next day! Store any remaining casserole in an airtight container in the refrigerator for up to 3-4 days. To reheat, place individual portions in an oven-safe dish and bake at 350°F (175°C) for 15-20 minutes, or until heated through. You can also reheat it in the microwave, but the oven helps retain the crispy cheese topping.

Frequently Asked Questions (Mushroom Polenta Casserole)

The Ultimate Comfort Food Awaits

This Mushroom Polenta Casserole recipe is more than just a meal; it’s a comforting, satisfying experience that brings a touch of rustic elegance to your table. We hope you love making and eating it as much as we do. If you try this recipe, please leave a comment below and let us know how it turned out! Don’t forget to share your creations with us on Pinterest.

Mushroom Polenta Casserole Recipe

Mushroom Polenta Casserole: A Creamy, Cheesy Delight

Discover the ultimate comfort food with this Mushroom Polenta Casserole recipe. A rich, savory mushroom ragout baked over creamy, cheesy polenta for a satisfying and elegant vegetarian meal.

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Prep Time 20 minutes mins

Cook Time 50 minutes mins

Total Time 1 hour hr 10 minutes mins

Servings: 6 servings

Course: Dinner, Main Course

Cuisine: American, Italian

Calories: 450

Ingredients Equipment Method Notes

Ingredients

  

For the Mushroom Ragout

• 1 tbsp Olive Oil
• 1 tbsp Unsalted Butter
• 1 Yellow Onion finely chopped
• 3 cloves Garlic minced
• 1 tbsp Fresh Thyme chopped
• 24 oz Mixed Mushrooms such as cremini, shiitake, and oyster, sliced
• 0.25 cup Dry White Wine like Sauvignon Blanc
• 1 tsp Salt to taste
• 0.5 tsp Black Pepper to taste

For the Creamy Polenta

• 3 cups Vegetable Broth
• 3 cups Whole Milk
• 1.5 cups Yellow Cornmeal (Polenta)
• 4 tbsp Unsalted Butter
• 1 cup Parmesan Cheese freshly grated
• 1 tsp Salt to taste

For Assembly

• 1.5 cups Gruyère Cheese shredded

Equipment

• 1 9x13 inch Baking Dish
• 1 Large Skillet
• 1 Medium Saucepan

Method

 

Prepare the Mushroom Ragout

1. In a large skillet or Dutch oven, heat olive oil and butter over medium heat. Add the chopped onion and cook until softened, about 5-7 minutes. Add the minced garlic and fresh thyme and cook for another minute until fragrant.
2. Increase the heat to medium-high, add the sliced mushrooms to the skillet. Cook, stirring occasionally, until they release their liquid and begin to brown, about 10-12 minutes.
3. Pour in the white wine to deglaze the pan, scraping up any browned bits from the bottom. Let it simmer until the wine has almost completely evaporated. Season with salt and pepper, then remove from heat and set aside.

Cook the Polenta

1. In a medium saucepan, bring the vegetable broth and milk to a simmer over medium-high heat.
2. Once simmering, slowly pour in the polenta while whisking continuously to prevent lumps from forming.
3. Reduce the heat to low and continue to cook, stirring frequently with a wooden spoon, until the polenta is thick and creamy, about 20-25 minutes.
4. Remove the polenta from the heat and stir in the unsalted butter and grated Parmesan cheese until fully melted and incorporated. Season with salt and pepper to taste.

Assemble and Bake

1. Preheat your oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish.
2. Spread the creamy polenta evenly into the bottom of the prepared baking dish.
3. Spoon the savory mushroom ragout over the polenta in an even layer.
4. Sprinkle the shredded Gruyère cheese evenly over the mushroom layer.
5. Bake for 20-25 minutes, or until the casserole is heated through and the cheese is melted, bubbly, and lightly golden.
6. Let the casserole rest for 5-10 minutes before serving. This allows it to set up slightly, making it easier to serve. Garnish with fresh parsley if desired.

Notes

Tip 1: For the creamiest polenta, whisk constantly as you pour it into the simmering liquid to avoid any lumps.
Tip 2: Don't overcrowd the mushrooms in the pan. Sauté them in batches if needed to ensure they brown properly rather than steam.
Tip 3: Freshly grating your cheese will result in a smoother melt and better flavor than pre-shredded cheese.