Preheat oven to 400°.
Cook pasta according to package directions, omitting salt and fat. Drain well.
Heat the oil in a Dutch oven over medium-high heat. Add red bell pepper strips and mushrooms; sauté 2 minutes. Add chicken, ginger, and garlic; sauté 3 minutes. Stir in soy sauce; cook 2 minutes, stirring frequently.
Combine broth and cornstarch, stirring well with a whisk. Add broth mixture to pan, and cook 2 minutes or until mixture is slightly thick, stirring constantly. Remove from heat; stir in sherry, vinegar, and crushed red pepper. Add pasta, bok choy, green onions, and 2 teaspoons sesame seeds to pan, tossing well to combine. Spoon pasta mixture into an 8-inch square baking dish lightly coated with cooking spray.
Combine breadcrumbs, butter, and remaining sesame seeds; sprinkle evenly over pasta mixture. Bake at 400° for 20 minutes or until breadcrumbs begin to brown.