Soak your lasagna noodles in water while you chop the vegetables; a long plastic container does the trick. Make sure that they are covered with water.
Place the olive oil and onions into a large skillet. Fry until the onions are tender-crisp, then add in the other vegetables. Continue to cook until the vegetables are tender-crisp.
Add in the spinach and cook until wilted. Remove the skillet from the heat.
To prepare the ricotta mixture, mix together the ricotta, egg, Italian seasoning and Parmesan. Set aside.
Preheat your oven to 350 °F while you prepare the lasagna layers.
Take the pasta sauce and in another bowl combine it with a cup of water. Then on the bottom of a 9x13 pan pour and spread out 1/2 a cup of the sauce.
Drain the noodles and then put your first layer on. Don't be afraid to do them patchwork, they do not fit perfectly. I used 4 across the width and one laying at the bottom and this used up the entire box of noodles.
Add another half a cup of sauce on top.
Use 1/3 of your fried veggies on top of that sauce.
Dab on a 1/3 of the ricotta mixture on top of those veggies.
Repeat the layers until you have only the top layer of noodles then pour the remainder of the sauce on top.
Cover with tinfoil and bake in a 350 degree oven for approximately 45 minutes or until the noodles are tender.
Remove from the oven and top with the mozzarella cheese then return the pan uncovered to the oven for another 10-15 minutes, until the cheese looks melted and slightly bubbled.
Let it sit for 5-10 minutes, then slice and serve.
Notes
you need approximately 6 cups of vegetables (excluding the onion and spinach) for this lasagna, Mix and match as you see fit!