Put chicken and onion through the meat grinder and into a large bowl. Add egg, salt, pepper, and tarragon to the bowl. Mix well by hand until the mixture is smooth. Form two big patties, place on plate or cutting board and flatten them.
Cut the ½ stick of butter in half and roll each half into a thin log. Coat with tarragon on all sides. Place one butter log in a middle of each patty, and reshape so that the chicken mixture covers the butter completely.
In a shallow dish, mix breadcrumbs, spices, and Parmesan. Coat the chicken patties with breadcrumbs. Refrigerate for at least 10 minutes.
Heat the oil in a skillet and brown the chicken patties quickly (1-2 minute per side).
Bake on 375° F, covered, for about 10 minutes or until golden brown. Serve with Peppers Tricolor and Truffled Mashed Potatoes.
To make Peppers Tricolor, roast the three different kinds of sweet bell peppers then drizzle them with balsamic vinegar. For Truffled Mashed Potatoes, simply add truffle oil to taste into your regular mashed potatoes. These sides compliment Chicken Kiev perfectly.
Now, take a look at what happens the moment you cut into the chicken.