Bring a pot of salted water to boil and cook al dente according to instructions. Do not overcook the noodles.
Chop all vegetables. Preheat oven to 350 degrees.
In a large skillet, heat oil and when ready, add in the onion, garlic, peppers and mushrooms, if adding. Cook for 3-4 minutes or until onions have softened.
Add in the seasoning and stir together for 1 more minute.
Add in frozen meatless crumbles. Cook for 4 minutes.
Pour in the marinara, 1 cup of the mozzarella, and the chopped pepperoni pieces. Stir to combine.
Drain pasta and add to the skillet. Stir to combine well.
Spoon mixture into a 9×13 baking dish.
Top with remaining vegan Mozzarella, parmesan, and the remaining sliced vegan pepperoni.
Cover the top with foil and bake for 25 minutes. If you avoid foil, you can cover with a baking sheet.
Remove foil and bake another 15 minutes until bubbly.
Remove from oven and let sit for 5-10 minutes.