Combine the garlic and fresh herbs. Add half of the mixture, as well as a pinch of salt, to the softened butter and mix well. Place the herb/butter mixture on a sheet of plastic and roll the plastic around the butter to form a tube. Reserve the other half of the herb/garlic mixture for seasoning the breasts. Refrigerate the butter.
Place each breast between in a gallon zip top bag. Pound the breasts to 1/4” thickness. being careful not to tear holes in the meat. Slice each flattened breast in half. Place the smooth side of the breasts down then season the breasts with Plowboys Fin & Feather and the reserved herb/garlic mixture. Divide the herb butter from the fridge into eight equal logs. Place one log in the center of each breast. Wrap up the breasts so the Kievs are as airtight as possible to keep the butter from leaking out on the grill. Fold over the breasts on the sides first, and then top and bottom. Wrap the Kievs in a slice of prosciutto. Pin with a toothpick and place them in the refrigerator for at least 30 minutes to firm up.
Preheat your Yoder Smokers YS640 to 275ºF. Place the Kievs in a foil pan and smoke until a thermometer inserted into the middle reads 165ºF, about 45 minutes. While the Kievs smoke, make the sauce. First, preheat a Lodge Logic 8” Cast Iron Skillet over medium heat. Add the olive oil. Dice the remaining two slices of prosciutto. Add the diced prosciutto and shallot to the oil and cook until shallot is softened. Add the flour and stir for about one minute. Add the white wine and lemon juice. Stir until thickened, scraping up anything stuck to the pan. You may finish the sauce with a pat of butter, if you wish. Finally, plate the Kievs and pour the sauce over them. Serve with lemon wedges.