Ham and Cheese Macaroni Bake with Peas

1 pound uncooked medium elbow macaroni
1 1/2 cups chopped lean ham 
1 1/2 cups frozen peas
Cooking spray
1/2 cup finely chopped onion 
3 cups 2% reduced-fat milk 
1 cup (4 ounces) shredded reduced-fat extrasharp cheddar cheese 
1 cup (4 ounces) shredded Swiss cheese 
3/4 teaspoon salt
1/4 teaspoon freshly ground black pepper 
1/8 teaspoon ground red pepper
2 (1-ounce) slices white bread 
2 tablespoons butter, melted 

Preheat oven to 400°. Cook pasta in boiling water 6 minutes. Drain and rinse with cold water; drain. Combine pasta, ham, and peas in a large bowl.
Heat a medium saucepan over medium heat. Coat pan with cooking spray. Add onion to pan; cook 4 minutes, stirring frequently. Add milk; bring to simmer. Remove from heat; stir in cheeses, salt, and peppers. Pour cheese mixture over pasta mixture; stir to coat. Spoon pasta mixture into a 13 x 9–inch baking dish coated with cooking spray.
Place bread in a food processor; pulse 10 times or until coarse crumbs measure 1 1/4 cups. Combine breadcrumbs and butter in a bowl. Arrange breadcrumb mixture evenly over pasta mixture. Bake at 400° for 20 minutes or until lightly browned. 
Serves 8.