Preheat oven to 375 degrees. Coat a 9 X 9-inch baking pan with cooking spray.
Cook the tortellini al dente (two minutes less than the time given on the package). Drain.
Place tortellini in a large bowl. Using a rubber spatula, carefully stir in Alfredo sauce, diced chicken, spinach, tomatoes, cottage cheese, and garlic powder until combined.
Place mixture in baking dish. Spread out to evenly distribute. Sprinkle mozzarella cheese evenly over pasta to cover. Then sprinkle Parmesan cheese all over top.
Bake 15 minutes, or until cheese is melted and light golden brown on top.
Cool slightly before cutting into 6 servings. This casserole freezes great.