Fill a pot or other heat-resistant container 1/3-1/2 full of hot or warm water. Preheat sous vide precision cooker to 146.5º Fahrenheit (63.6º Celsius).
Brush or rub olive oil evenly over both sides of chicken breasts. Season with plenty of salt; crack fresh black pepper over.
Place chicken breasts in a one-gallon Ziploc bag along with fresh herbs. Vacuum seal or use water displacement method to seal (See note 1). Place in water bath.
Cook for 1 hour. After 1 hour, remove bags and discard any herbs or garlic used. Remove chicken breasts and pat very dry with paper towels. Heat a medium skillet over medium-high heat until hot.
Add butter; when foaming, carefully add chicken breasts. Cook 1 minute per side or until nicely browned. Serve right away; there is no need to rest after cooking poultry sous vide.
Note 1: Include 1-2 cloves peeled and smashed garlic in your bag with the chicken and fresh herbs for even more flavor.
Note 2: To seal bags with water displacement method: Place all ingredients in a one-gallon Ziploc bag and seal halfway across the top. Slowly lower the bag into the water bath, making sure the water pressure pushes the air out as you go. The bag will cling to the chicken breasts when this happens. Once ingredients are entirely submerged (They will almost always sink, not float), seal the rest of the bag. Proceed with the recipe.
Note 3: I prefer to use butter here, as it will brown much faster than regular oil. However, you can absolutely use ghee, avocado oil, or refined coconut oil; it will simply not brown the chicken breasts as well. I avoid using olive oil at such a high heat.
Whole30 Note: If you're on a Whole30, you must use ghee or oil when finishing this sous vide chicken breast recipe instead of butter. Ghee is fantastic here!