There is something undeniably nostalgic about a rice casserole, but this Savory Mushroom Rice Casserole is a major upgrade from the canned-soup versions of the past. It’s a rich, earthy, and deeply satisfying side dish (or vegetarian main!) that brings out the best in simple ingredients like long-grain rice and fresh baby bella mushrooms.
The secret to this dish is twofold: first, we sauté the mushrooms until they are deeply browned to unlock their full “umami” potential. Second, we bake the rice directly in a seasoned broth, allowing it to soak up every bit of flavor while achieving a perfect, tender fluffiness. Whether you’re looking for a holiday side dish or a cozy weeknight comfort meal, this casserole is a guaranteed crowd-pleaser.
Why You’ll Love This Recipe
- Deep Umami Flavor: Caramelizing the mushrooms creates a savory depth that pairs perfectly with rice.
- Easy One-Dish Bake: Minimal prep and simple stovetop-to-oven transition.
- Versatile: Works as a hearty side for roasted meats or as a standalone vegetarian dinner.
- Better than Canned: No “cream of mushroom” soup needed—we create our own rich, flavorful base.
Recipe Card Info
- Prep Time: 10 minutes
- Cook Time: 40 minutes
- Total Time: 50 minutes
- Servings: 6
- Dietary: Vegetarian, Gluten-Free
Ingredients
For the Casserole:
- 2 cups long-grain white rice (rinsed)
- 1 lb baby bella (cremini) mushrooms, sliced
- 4 Tbsp unsalted butter
- 1 medium onion, finely diced
- 3 cloves garlic, minced
- 4 cups vegetable or chicken broth
- 1/2 cup grated Parmesan cheese
- 1 tsp dried thyme
- 1/2 tsp onion powder
- Salt and freshly ground black pepper to taste
- Fresh parsley for garnish
Instructions
- Sauté Mushrooms: Preheat your oven to 375°F (190°C). In a large oven-safe skillet or Dutch oven, melt 2 tablespoons of butter over medium-high heat. Add the mushrooms and cook undisturbed for 3-4 minutes until browned. Stir and cook for another 3 minutes until tender. Remove mushrooms and set aside.
- Aromatics: In the same pot, melt the remaining 2 tablespoons of butter. Add the onion and sauté for 5 minutes until translucent. Stir in the garlic, thyme, and onion powder, cooking for just 1 minute until fragrant.
- Toast Rice: Add the rinsed rice to the pot with the onions. Stir for 2 minutes to lightly toast the grains; this adds a nutty flavor and prevents the rice from getting mushy.
- Combine: Stir the browned mushrooms back into the pot. Pour in the broth and season with salt and pepper. Bring the mixture to a simmer.
- Bake: Cover the pot tightly with a lid (or foil) and transfer to the oven. Bake for 25–30 minutes, or until the liquid is fully absorbed and the rice is tender.
- Finish: Remove from the oven and let it sit, covered, for 5 minutes. Fluff with a fork, then stir in the grated Parmesan cheese.
- Serve: Garnish with fresh parsley and extra black pepper. Serve warm.
Chef’s Tips for Success
- Tip 1 (Mushroom Browning): Don’t salt the mushrooms at the start of cooking. Salt draws out moisture, which causes them to steam instead of sear. Wait until they are brown before seasoning!
- Tip 2 (The Right Rice): Long-grain white rice or Basmati works best here. Avoid short-grain or sushi rice, as they contain too much starch and will make the casserole gummy.
- Tip 3 (Broth Temperature): Bringing the broth to a simmer on the stove before putting the pot in the oven ensures the rice starts cooking immediately and evenly.
Encouraging Conclusion
This Mushroom Rice Casserole is a testament to how elegant simple ingredients can be when treated with a little care. It’s warm, earthy, and feels like a hug in a bowl.
