Pat the raw chicken breasts dry with a paper towel, and slice the chicken lengthwise to make two thinner cutlets out of each, for four total pieces.
Season the chicken all over with salt, pepper, and garlic powder.
In a large skillet, heat olive oil until hot and shimmering (but not smoking). Add the chicken and cook until golden brown, without moving them, for 7-8 minutes. Turn them over and continue cooking until the internal temperature of the chicken is 165°F when an instant-read thermometer is inserted in the thickest areas of chicken.
Transfer the chicken to a plate, shaking off excess juices, while you make the pan sauce. Add the lemon juice and water, white wine, or chicken stock and cook for 2 minutes over medium heat. Scrape up any brown bits from the bottom of the pan.
Turn the heat off and add the butter, stirring until melted. Place the chicken pieces back into the sauce and warm through on low heat. Tuck the lemon slices around the chicken, dust with lemon zest and parsley. Serve immediately.