Prepare the chicken breasts by removing the wing bones and flattening them to 1/4-inch thickness.

Prepare the herb butter by creaming together butter, chives, parsley, tarragon, mustard, salt, and pepper.

Place 2 tablespoons of herb butter in the center of each chicken breast.

Cover the butter with a fillet strip and fold the sides of the chicken to enclose the butter.

Dredge the chicken in flour, shaking off the excess.

Dip the chicken in the beaten egg mixture.

Coat the chicken thoroughly with bread crumbs, patting them onto the flesh.

Chill the breaded chicken for at least 1 hour to let the crumbs dry.

Heat vegetable oil in a large skillet over moderate heat.

Brown the chicken in the hot oil.

Transfer the browned chicken to a baking pan.

Bake in a preheated 350 degree oven for 20 minutes.

Keep warm, covered loosely, for up to 10 minutes before serving.