Preheat the oven to 375°F.

Bring a large pot of salted water to a boil.

In a skillet, over medium heat, add 1 teaspoon of olive oil and let heat. Add the spinach and cook, stirring occasionally, until it is wilted. Remove the spinach from the skillet and place in a colander. Use a wooden spoon to press out any excess moisture. Set aside.

In the same skillet, heat the remaining 2 teaspoons of oil. Add the zucchini, yellow squash, bell pepper, and carrots. Sauté on medium heat until the vegetables are tender, about 4-5 minutes. Add the garlic, dried oregano, dried basil, and salt and pepper, and cook for another 1-2 minutes. Drain any extra liquid from the veggies and set aside.

To make the white sauce, melt the butter over medium heat in a small saucepan. Add the flour and whisk continuously to form a roux. Lower the heat to medium/low.

Gradually pour in the milk while whisking to avoid lumps. Continue to whisk until the mixture thickens.

Stir in the grated Parmesan cheese, a little at a time, until smooth and melted. Season with salt and pepper and remove from heat.

While the white sauce is cooking, boil the noodles according to package instructions and drain well.

In a greased 9x13-inch baking dish, spread a thin layer of white sauce.

Place a layer of cooked lasagna noodles on top of the white sauce.

Add half of the spinach and sautéed vegetables evenly over the noodles, followed by a layer of white sauce and ¼ of the mozzarella cheese.

Repeat for the next layer.

Add a final layer of noodles, white sauce, and remaining ½ of shredded mozzarella cheese evenly over the white sauce.

Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.

Remove the foil and bake for an additional 15-20 minutes or until the cheese is golden and bubbly.

Allow the lasagna to rest for 10 minutes before sprinkling with parsley and slicing into 9 pieces.