Boil chicken until cooked through.

Debone the cooked chicken, reserving the broth.

Cook vermicelli pasta in the reserved chicken broth.

Chop green peppers and onions.

Sauté chopped onions and green peppers in margarine until softened.

In a large bowl, combine the sautéed vegetables, Ro-Tel tomatoes, Worcestershire sauce, mushrooms, and Velveeta cheese.

Stir the mixture until the cheese is completely melted and smooth.

Tear the deboned chicken into small, bite-sized pieces.

Add the torn chicken to the cheese and vegetable mixture.

Stir well to combine all ingredients thoroughly.

If needed, add some of the chicken broth to ensure the casserole is moist.

Pour the mixture into a baking dish.

Bake at 350°F (175°C) until hot and bubbly, approximately 60 minutes.