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Creamy Mushroom Cauliflower Bake - Cozy, Comforting, and Easy

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Prep Time 15 minutes
Cook Time 30 minutes
Total Time 45 minutes
Servings: 6 servings
Ingredients Method

Ingredients
  

  • 1 large head of cauliflower, cut into bite-size florets
  • 1 pound mushrooms (cremini, button, or mixed), sliced
  • 1 medium yellow onion, finely chopped
  • 3 cloves garlic, minced
  • 2 tablespoons unsalted butter (plus 1 tablespoon for the topping)
  • 2 tablespoons olive oil
  • 2 tablespoons all-purpose flour
  • 1 1/2 cups whole milk or half-and-half
  • 1/2 cup low-sodium vegetable or chicken broth
  • 1 teaspoon Dijon mustard
  • 1/2 teaspoon dried thyme or 1 teaspoon fresh thyme leaves
  • 1/4 teaspoon ground nutmeg (optional but lovely)
  • 1 1/2 cups shredded Gruyère or Swiss cheese (or a mix with mozzarella)
  • 1/2 cup grated Parmesan cheese
  • 1 cup panko breadcrumbs
  • Salt and freshly ground black pepper
  • Fresh parsley, chopped (for garnish, optional)

Method
 

  1. Prep and preheat: Heat your oven to 425°F (220°C). Lightly grease a 9x13-inch baking dish. Pat the cauliflower florets dry so they roast instead of steam.
  2. Roast the cauliflower: Toss florets with 1 tablespoon olive oil, a pinch of salt, and pepper. Spread on a sheet pan and roast 18–22 minutes, flipping once, until lightly browned and just tender.
  3. Sauté the mushrooms: While the cauliflower roasts, heat 1 tablespoon olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add mushrooms with a pinch of salt and cook 6–8 minutes, stirring occasionally, until they release moisture and start to brown.
  4. Cook the aromatics: Reduce heat to medium. Add the onion and cook 3–4 minutes until translucent. Stir in garlic and thyme; cook 30 seconds until fragrant.
  5. Build the roux: Sprinkle in the flour and stir to coat the vegetables. Cook 1 minute to remove raw flour taste.
  6. Add liquids: Whisk in milk (or half-and-half) gradually, then broth. Stir in Dijon and nutmeg. Simmer 3–5 minutes, stirring, until the sauce thickens enough to coat a spoon. Season with salt and pepper to taste.
  7. Add the cheese: Off heat, stir in 1 cup shredded Gruyère (or Swiss) and 1/4 cup Parmesan until melted and smooth. Reserve the remaining cheeses for topping.
  8. Assemble: Reduce oven to 375°F (190°C). Add roasted cauliflower to the baking dish. Pour the creamy mushroom sauce over and gently toss to coat and distribute evenly.
  9. Make the crunchy top: In a small bowl, melt 1 tablespoon butter. Combine with panko, remaining Gruyère, and remaining Parmesan. Season with a little pepper.
  10. Bake: Sprinkle the topping over the casserole. Bake 18–22 minutes, until bubbling around the edges and golden on top.
  11. Rest and serve: Let it stand 5–10 minutes to set. Garnish with chopped parsley if you like, then serve warm.