Pat the chicken breasts dry with a paper towel and remove any loose fat bits. Slice the breasts in half. If using chicken cutlets, you don't need to slice them.
Season well with lemon pepper and salt on all sides.
Heat up your skillet over medium heat and add the olive oil when the pan is hot.
When the olive oil is hot, add the chicken cutlets and brown them on both sides. When they've almost reached 165 degrees Fahrenheit (74 degrees Celsius), remove them to a plate and set to the side.
In the same pan, add the other tablespoon of olive oil. Add the finely diced onion, minced garlic, thyme and the zest of 3 lemons and sauté until onions start to soften.
Add the wine and the juice of 1 lemon and let the wine cook off. Add the chicken stock. Let it cook on medium heat for 5 minutes, to have your sauce reduce a little bit.
Over medium-low heat, add the butter 1 tablespoon at a time, mixing it with a whisk to emulsify your sauce.
Add the chicken back in with all the juices from the plate and turn the heat off.
Garnish with some lemon slices and some finely chopped fresh parsley. Serve over rice, mashed potatoes, or even pasta.