1. Prepare and Roast the Vegetables:
* Preheat your oven to 400°F (200°C).
* On a large baking sheet (or two if necessary to avoid overcrowding), combine the chopped bell peppers, zucchini, mushrooms, and red onion.
* Drizzle with 3 tablespoons of olive oil, sprinkle with minced garlic, Italian herbs, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Toss everything well to ensure the vegetables are evenly coated.
* Spread the vegetables in a single layer.
* Roast for 20-25 minutes, stirring halfway, until the vegetables are tender-crisp and slightly caramelized. You don’t want them mushy. Once done, remove from the oven and set aside. You can slightly lower the oven temperature to 375°F (190°C) for baking the lasagna later.

2. Sauté the Spinach and Kale:
* While the vegetables are roasting, heat 1 tablespoon of olive oil in a large skillet or Dutch oven over medium heat.
* Add the thinly sliced garlic and cook for about 30 seconds until fragrant, being careful not to burn it.
* Add the kale to the skillet. Sauté for 2-3 minutes until it begins to wilt.
* Add the baby spinach in batches, stirring until it wilts down.
* Season with a pinch of salt and nutmeg. Cook until all the liquid released by the greens has mostly evaporated. Remove from heat and set aside.

3. Make the Béchamel Sauce:
* In a large saucepan or Dutch oven, melt 6 tablespoons of butter over medium heat.
* Once the butter is melted and foamy, whisk in the 1/2 cup of flour. Cook, whisking constantly, for 1-2 minutes to form a smooth roux (this cooks out the raw flour taste).
* Gradually whisk in the warmed milk, a little at a time, ensuring each addition is fully incorporated before adding more. This prevents lumps.
* Continue whisking constantly until the sauce comes to a gentle simmer and begins to thicken – about 5-8 minutes. It should be thick enough to coat the back of a spoon.
* Remove from heat. Stir in 1 teaspoon salt (or to taste), white pepper, nutmeg, and 1/2 cup of grated Parmesan cheese. If using, stir in the heavy cream. Taste and adjust seasonings if necessary. Set aside. To prevent a skin from forming, you can press a piece of plastic wrap directly onto the surface of the sauce.

4. Prepare the Ricotta Filling:
* In a medium bowl, combine the ricotta cheese, beaten egg, 1/2 cup Parmesan cheese, chopped fresh parsley, chopped fresh basil, 1/2 teaspoon salt, and 1/4 teaspoon black pepper.
* Mix well until everything is thoroughly combined. Set aside.

5. Cook Lasagna Noodles (If Not Using Oven-Ready):
* If you’re not using oven-ready (no-boil) lasagna noodles, cook your regular lasagna noodles according to the package directions until al dente. Drain them well and lay them flat on a lightly oiled baking sheet or parchment paper to prevent sticking.

6. Assemble the Lasagna:
* Preheat oven to 375°F (190°C) if you haven’t already.
* Lightly grease a 9×13 inch (23×33 cm) baking dish.
* First Layer: Spread a thin layer (about 1 cup) of the béchamel sauce evenly over the bottom of the baking dish. This prevents the noodles from sticking and helps them cook.
* Second Layer: Arrange a layer of lasagna noodles over the sauce, slightly overlapping if necessary.
* Third Layer: Spread half of the ricotta mixture evenly over the noodles.
* Fourth Layer: Distribute half of the roasted vegetables over the ricotta.
* Fifth Layer: Scatter half of the sautéed spinach and kale mixture over the roasted vegetables.
* Sixth Layer: Drizzle about 1 to 1.5 cups of the béchamel sauce over the greens.
* Seventh Layer: Arrange half of the fresh mozzarella slices over the béchamel.
* Repeat Layers: Add another layer of lasagna noodles. Spread the remaining ricotta mixture, then the remaining roasted vegetables, and the remaining sautéed spinach and kale. Drizzle with another 1 to 1.5 cups of béchamel sauce and top with the remaining fresh mozzarella slices.
* Final Layer: Top with a final layer of lasagna noodles. Pour the remaining béchamel sauce over the noodles, ensuring the top is completely covered. This is key for creamy, non-dry edges.
* Cheese Topping: Sprinkle the 1 cup of shredded low-moisture mozzarella cheese and 1/2 cup of grated Parmesan cheese evenly over the top.

7. Bake the Lasagna:
* Cover the baking dish loosely with aluminum foil (you can tent it slightly or grease the underside of the foil to prevent cheese from sticking).
* Bake for 30 minutes.
* Remove the foil and continue to bake for another 20-25 minutes, or until the top is golden brown and bubbly, and the sauce is bubbling around the edges. If the top starts to brown too quickly, you can loosely tent it with foil again.

8. Rest the Lasagna:
* Once baked, remove the lasagna from the oven and let it rest for at least 15-20 minutes before slicing and serving. This is crucial! It allows the layers to set, making it much easier to cut neat slices and preventing it from turning into a molten mess.

9. Serve:
* Garnish with fresh basil leaves, if desired. Slice into generous portions and serve warm.