Preheat your oven to 400°F.

Toss the diced zucchini, squash, bell pepper, and mushrooms with olive oil, salt, and pepper. Roast veggies in the oven for 20 minutes.

In a saucepan, melt butter and whisk in flour. Cook for 1 minute. Slowly whisk in milk and simmer for 5-7 minutes until thick. Season with salt, pepper, and nutmeg.

In a bowl, mix together ricotta, egg, Parmesan, garlic powder, and more salt and pepper.

If using regular lasagna noodles, boil them now.

In a greased 9x13 baking dish, layer some béchamel sauce, followed by noodles, half of the ricotta mixture, half of the roasted veggies, spinach, and more béchamel. Repeat these layers.

Top with the final noodles, béchamel, and a generous handful of mozzarella.

Cover with foil and bake at 375°F for 30 minutes. Uncover and bake for an extra 10-15 minutes until golden.

Let rest for 10 minutes before serving. Garnish with parsley if desired.