Heat butter in a large skillet over medium heat. Sauté onion and red pepper until tender, about 2 to 3 minutes.
Stir in peas and cream cheese, stirring until cheese is melted. Add cream, blue cheese, garlic powder, parsley, Italian seasoning, white pepper and salt. Stir just until cheese is melted and mixture is thoroughly heated. Do not boil.
Toss with cooked tortellini. Sprinkle with walnuts and serve immediately.