Clean and cut the mushrooms and bell peppers into small pieces.
Bring a large pot of water to boil and add the pasta. Cook until al dente, about 8-10 minutes, then drain.
While the pasta is cooking, heat a large pan over medium-high heat. Add the gyros meat and fry for 5-7 minutes until heated through and browned. Add the bell peppers, mushrooms, and frozen peas. Season with thyme, rosemary, and Italian herbs. Cook for another 2-3 minutes.
Transfer the drained pasta to a baking dish. Sprinkle with half of the grated cheese. Layer the gyros meat and vegetables on top. Pour the hollandaise sauce evenly over the mixture. Sprinkle the remaining grated cheese on top.
Bake in the oven at 180°C (356°F) for about 15-20 minutes until the cheese is lightly browned.