For the White Sauce (Béchamel):

• 4 tbsp unsalted butter – Adds richness to the sauce.
• 4 tbsp all-purpose flour – Helps thicken the sauce for a smooth texture.
• 4 cups whole milk – Creates a velvety, creamy consistency.
• 1 tsp salt – Enhances the overall flavor.
• ½ tsp black pepper – Adds a subtle spice.
• ½ tsp garlic powder – Gives a mild savory depth.
• ¼ tsp ground nutmeg – Complements the creaminess with warmth.
• ½ cup grated Parmesan cheese – Provides a rich, cheesy finish.

For the Vegetable Filling:

• 2 tbsp olive oil – For sautéing the vegetables.
• 1 small onion, finely chopped – Adds sweetness and flavor.
• 2 cloves garlic, minced – Enhances the dish with a bold aroma.
• 1 cup mushrooms, sliced – Provides a meaty texture.
• 1 zucchini, diced – Adds freshness and a mild crunch.
• 1 red bell pepper, diced – Brings sweetness and color.
• 2 cups fresh spinach – Wilts beautifully for added nutrition.
• ½ tsp dried oregano – Infuses the filling with Italian flavors.
• ½ tsp dried basil – Adds an aromatic, herby note.
• Salt and black pepper to taste – Enhances overall flavor balance.

For Assembling the Lasagna:

• 12 lasagna noodles, cooked – Use oven-ready noodles for convenience.
• 1 ½ cups ricotta cheese – Makes the layers creamy and smooth.
• 2 cups shredded mozzarella cheese – Provides a gooey, melty texture.
• ½ cup grated Parmesan cheese – Enhances the cheesy layers.
• Fresh basil or parsley, chopped (for garnish) – Adds a fresh finishing touch.