Preheat oven to 350°F
In a large skillet, heat the olive oil over medium heat
Add the diced onion and cook for 2–3 minutes until softened
Add the garlic and cook for 30 seconds until fragrant
Add the zucchini, squash, carrots, oregano, basil, salt, and pepper
Cook for 5–7 minutes, stirring occasionally, until the vegetables begin to soften
Add the mushrooms and cook for another 2–3 minutes
Pour in the crushed tomatoes, stir, and reduce heat to low
Simmer for 5 minutes, then taste and adjust seasoning if needed
In a bowl, mix the ricotta cheese with a pinch of salt and pepper
Spread a thin layer of the vegetable sauce on the bottom of a 9x13-inch baking dish
Place 3 no-boil lasagna noodles on top
Spread 1/3 of the ricotta mixture over the noodles
Add half of the vegetable mixture and spread evenly
Sprinkle a small handful of mozzarella cheese
Add another layer of 3 lasagna noodles
Spread another 1/3 of the ricotta mixture
Add the remaining vegetable mixture
Top with the final 3 lasagna noodles
Spread the remaining ricotta on top
Sprinkle the remaining mozzarella cheese evenly over the top
Cover the dish with foil
Bake for 40–45 minutes until hot and bubbly
Remove foil and broil for 2–3 minutes until the top is lightly golden
Let rest for 10–15 minutes before slicing
Serve and enjoy