In a large bowl, mix together breadcrumbs, ground chicken, egg, dill, parsley, mustard, salt and pepper; mix well. With dampened hands, form the mixture into 6-8 1/2-inch-thick patties, using about 1/2 cup for each.
Coat skillet and heat over medium-high heat. Place patties on heated skillet, flip patty after about 5 minutes. Cook until thermometer inserted in center of patty reads 165F.
Toast buns lightly when burgers are finished and serve. Garnish with lettuce, tomato and onions if desired.