Mixbutter, tarragon, parsley, chives, thyme, 1 teaspoon salt, and a tip of a teaspoonof pepper in a bowl.
Spoon mixture onto some plastic wrap, orparchment paper, and roll into a 1-inch-thick log.
Wrap tightly; freeze until firm; between 3 hoursand 3 days.
Slice frozen butter into 6 equal pieces.
Put a chicken breast between 2 pieces of plasticwrap, or 2 large resealable plastic bags.
Hit with a Rolling Pin to 1/4-inch-thick.
Move onto a clean piece of plastic wrap. Season well.
Put a piece of herbed butter in the middle of thechicken.
Using the plastic wrap, tightly roll up the chickenstarting at a long side, tucking in the short sides as you work.
Tightly wrap the chicken rolls in plastic wrap.
Repeat with the remaining chicken and butter.
Chill chicken rolls in the fridge for at least 2hours or overnight.
Preheat the oven to 350 degrees F and set a wirerack on a rimmed baking sheet.
Put the flour in a shallow dish.
Whisk the eggs and mustard in 2nd shallowdish.
Put the Panko Breadcrumbs in a 3rd shallow dish.
Unwrap the chicken rolls and generously season well.
One at a time, roll the chicken rolls in flour,then dip in the egg mixture and roll in the panko to coat with the breadcrumbs.
Heat vegetable oil in a large skillet overmedium-high heat – about 1 and ½ inches high.
Fry the chicken rolls in 2 batches of 3,turning, until golden brown, 6 to 8 mins.
Move fried chicken to prepared rack and bakeuntil cooked through about 10 minutes.