For the marinade, whisk together all the ingredients except the chicken until well-combined.
Place chicken in shallow dish and pour the marinade over the chicken, turning the chicken to coat evenly. Cover the dish and refrigerate for 8-12 hours.
Grill the chicken on medium-high, about 3-4 minutes per side (exact time will depend on the thickness of the chicken) until cooked through and an instant-read thermometer registers 165 degrees F at the thickest part of the chicken. Tent the chicken with foil and let rest for 10 minutes before slicing and serving.
Ranch Dressing: I've used both Hidden Valley and a Trader Joe's brand of ranch dressing in this recipe, and both work great (with no noticeable flavor difference). Chicken: 1 1/2 to 2 pounds of chicken will be about 5-6 thin chicken breasts. I prefer using thin sliced chicken breasts (if the chicken breasts I'm using are overly thick, I slice them in half lengthwise for thinner cutlets). you can cube the chicken prior to marinating and then thread on kabobs after marinating and grill that way. Rosemary: subbing dried rosemary will affect the flavor of the chicken (highly recommend using fresh rosemary for better flavor).Oven Directions: broil or bake at 350 degrees F on a lightly greased foil-lined baking sheet for 3-4 minutes per side. Add or decrease time, as needed, depending on the thickness of the chicken.