In a mixing bowl, combine softened unsalted butter with minced garlic, chopped parsley, and fresh rosemary and thyme. Add salt and lemon juice. Blend until well mixed, then shape into a log and refrigerate for 30 minutes.

Butterfly each chicken breast and pound to an even thickness of about ¼ inch. Season with salt and pepper.

Place a piece of herb butter in the center of each chicken breast. Fold over and seal edges. Wrap in plastic wrap and freeze for 30 minutes.

Coat each chicken piece in flour, dip in beaten eggs, then coat with panko breadcrumbs.

Heat vegetable oil in a skillet over medium-high heat. Fry coated chicken for 1 minute on each side until golden brown. Transfer to a baking sheet and bake at 400°F (200°C) for 15-20 minutes, until internal temperature reaches 165°F (74°C).

Let Chicken Kiev rest for 5 minutes before serving with mashed potatoes or a salad.