Make the sauce: Process all ingredients in a food processor until smooth, stopping to scrape down sides.
Preheat oven to 350°F.
Stir together the chicken, cream cheese, spinach, garlic salt, and pepper.
Layer a lightly greased 11x7 inch baking pan with one-third of the Red Bell Pepper sauce, 3 noodles, one-third chicken mixture, and one-third cheese. Repeat layers twice. Place baking dish on a baking sheet.
Bake, covered, for 50 to 55 minutes. Uncover and bake 15 minutes longer.