In a medium size bowl, mix the ricotta cheese with the chopped spinach and egg. Mix well and set aside.
Heat a large pan on medium heat and add the olive oil, then add the zucchini, peppers, mushrooms, and onion. Cook until vegetables have softened, then drain any liquid that has formed.
Add the garlic and cook for about a minute, then add the oregano, basil, chilli flakes, tomato sauce and tomato paste. Cook just until the sauce is heated through.
Set oven to 350 degrees and begin assembling the lasagna
Spread a thin layer of sauce over the bottom of the pan, then add a layer of noodles.
Spread 2/3 of the remaining sauce over the noodles, then add a second layer of noodles.
Next spread the ricotta mixture evenly over the lasagna then add the third layer of noodles.
Spread the remaining sauce over the noodles, then add the shredded cheese.
Cover with aluminium foil and bake for approximately 30 minutes.
After 30 minutes you should see the sauce bubbling when you remove the foil. If not, return to the oven until it does. Then remove the foil, turn the oven to broil, and broil for about 5 minutes or until cheese is bubbly.