Preheat oven to 350F. In a large saute pan, saute onion for 2 minutes or just before caramelization. Then, add in chopped bell peppers, sliced mushrooms, and zucchini. Allow to simmer for about 5-7 minutes, stirring occasionally. Then, season with the above seasonings. Add in diced tomatoes next and allow to simmer for an additional 3-4 minutes.
In the meantime, drain and rise your palmini lasagna noodles. In an 8×8 pan (or larger if serving more). Line the bottom with a line layer of the veggie mixture. Then, layer with the lasagna layer. Next, add in more veggies and then cheese. Top it off with a layer of the lasagna noodles. Then, repeat the above until you reach the top of the dish.
Sprinkle cheese on the top and bake in the oven at 350F for 30 minutes. Allow to cool for 5-10 minutes before cutting into. ENJOY!