Cook dumplings according to package directions, omitting salt and fat.
Meanwhile, heat olive oil in a large nonstick skillet over medium heat. Sauté mushrooms 2 minutes or until soft. Add garlic; sauté 1 minute. Reduce heat to low; stir in Alfredo sauce and next 3 ingredients. Stir in spinach. Cook 3 minutes or until thoroughly heated and spinach wilts.
In a large bowl, combine dumplings and sauce. Sprinkle with cheese and black pepper; toss well. Serve immediately.