Cook pasta according to package directions.

Rinse pasta with cold water and drain well.

Cube the mozzarella cheese and cooked chicken.

Chop the green pepper and red pepper.

Slice the fresh mushrooms and green onions.

Halve the pepperoni slices.

In a large serving bowl, combine the cheese, chicken, peppers, mushrooms, olives, green onions, pepperoni, and pasta.

In a small bowl, whisk together the vegetable oil, red wine vinegar, Italian seasoning, garlic powder, salt, and pepper.

Pour the dressing over the salad and toss to coat.

Cover and refrigerate until ready to serve.

Toss again before serving.