Vegetable Mushroom Casserole Bake (Printable Version)

Roasted vegetables and mushrooms combine in creamy sauce, topped with golden cheese and breadcrumbs for hearty comfort.

# Ingredient List:

→ Vegetables

01 - 1 medium zucchini, sliced
02 - 2 medium carrots, peeled and sliced
03 - 1 red bell pepper, diced
04 - 1 cup broccoli florets

→ Mushrooms

05 - 10 ounces cremini or button mushrooms, sliced

→ Aromatics & Herbs

06 - 1 medium onion, finely chopped
07 - 2 garlic cloves, minced
08 - 1 tablespoon fresh thyme leaves or 1 teaspoon dried thyme

→ Sauce

09 - 2 tablespoons olive oil
10 - 2 tablespoons all-purpose flour
11 - 1 cup vegetable broth
12 - 1 cup whole milk or unsweetened plant-based milk
13 - Salt and black pepper, to taste

→ Topping

14 - 1 cup grated cheese (cheddar, Gruyère, or vegan cheese alternative)
15 - 1/2 cup breadcrumbs
16 - 1 tablespoon olive oil or melted butter

# Directions:

01 - Preheat oven to 400°F. Grease a large casserole or baking dish.
02 - In a large skillet over medium heat, warm 1 tablespoon olive oil. Sauté chopped onions until translucent, about 3 minutes. Add minced garlic and cook 30 seconds until fragrant.
03 - Add sliced mushrooms to the skillet. Sauté until softened and most liquid has evaporated, about 5 minutes.
04 - Add zucchini, carrots, bell pepper, and broccoli. Cook, stirring frequently, for 5 minutes or until vegetables are just tender. Stir in thyme with salt and black pepper to taste.
05 - Sprinkle flour evenly over vegetables. Stir and cook for 1 minute. Slowly pour in vegetable broth and milk, stirring constantly to prevent lumps. Continue to stir until a smooth, creamy sauce forms. Simmer 2–3 minutes to thicken slightly.
06 - Pour vegetable mixture into the prepared casserole dish. Smooth the top with a spatula.
07 - In a mixing bowl, combine grated cheese, breadcrumbs, and 1 tablespoon olive oil or melted butter. Mix thoroughly and sprinkle evenly across the casserole surface.
08 - Bake the casserole uncovered for 30–35 minutes, or until the topping is golden and the filling is bubbling.
09 - Allow to cool for 5 minutes before serving to set.

# Expert Advice:

01 -
  • It feels secretly luxurious with minimal fuss: the kind of meal that seems like it took all day, but didn't.
  • This casserole actually gets even better the next day, making leftovers a treat, not a chore.
02 -
  • Skimping on the mushroom sauté will leave your casserole watery and bland—give them time to truly brown.
  • Swapping in oats for breadcrumbs once resulted in a disappointingly chewy topping; classic breadcrumbs really are best.
03 -
  • Give every layer a quick taste for seasoning rather than only at the end—this guarantees flavor in every bite.
  • If you use vegan cheese, grating and mixing different brands boosts melt and flavor.
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