Preheat oven to 450°F. Line a large baking pan (you may need two pans) with parchment paper or grease well with non-stick cooking spray.
Spread mushrooms and tomatoes, cut side up, evenly onto prepared pan(s).
Sprinkle with garlic powder, dried oregano, salt and pepper. Then drizzle with olive oil.
Roast for 22-25 minutes, or until mushrooms are golden brown and tomatoes begin to split.
While mushrooms and tomatoes are roasting, cook pasta according to package directions until al dente.