Lay all your boneless skinless chicken breasts in a rimmed pan/dish that will fit all your chicken, without layering.
6 fresh boneless skinless chicken breasts
Salt both sides of the breasts, generously!!
kosher salt
Smash your garlic cloves so they are cracked and the insides are exposed, but do not mince or chop the garlic.Nestle it around the chicken.
6 fresh whole garlic cloves
Pour the buttermilk around the edges of the chicken, then shimmy the pan/chicken to make sure the buttermilk is surrounding the chicken. Tip: Don't pour the buttermilk directly over the chicken, you want to salt to stay somewhat adhered to the chicken.
2 cups buttermilk
Cover the pan and pop in the fridge for 12-24 hours. Pro Tip: if you don't have tight fitting lid on your chicken dish and have lots of kids grabbing things out of your fridge, I recommend placing the pan with the chicken and buttermilk on a rimmed baking sheet to catch any spills or accidents.!
Grilling Buttermilk Chicken
Set your grill up for direct and indirect grilling. If you have a charcoal grill this means that you will pile all your hot coals on one side of the kettle.
Remove the chicken from the buttermilk and place on a paper towel lined baking sheet. Let some of the buttermilk drain from the chicken. Give it a pat with some extra paper towels to absorb any excess buttermilk. However, it is ok if there is still some milk left on the chicken.See photo for reference.
Leave your chicken at room temp while your grill heats up! This is called tempering and will help your chicken cook more evenly.
When your grill is hot and ready place the chicken breast over the coals/heat for direct heat grilling, about 4 minutes on the first side.
Once the chicken will easily release from the grill flip it to the second side. Grill for another 4 minutes.
Now move the chicken to the indirect grilling side. Check the temp, if it has not reached 160° internal temp then pop the lid on the grill and cook over indirect heat until the chicken reaches an internal temp of 160°-165°. This could be anywhere from 1 minute to 5 minutes depending how large your chicken breasts are.
Remove your fully cooked chicken from the grill and let it sit for 5 minutes before cutting or serving. I do not like to tent with foil, this will prolong the carryover cooking and possibly over cook your chicken.
Video
Notes
Boneless Skinless Chicken Breasts: I absolutely recommend buying the very best chicken breasts you can, whether that is from a butcher or a really good brand (like Smart Chicken). Finding one that is air chilled is a great indication that it will be quality poultry.
If you have really thick/large chicken breasts I recommend splitting them lengthwise into two thinner breasts! They will marinate better and cook more evenly.
Don't be shy with the salt. Give it a good bath in kosher salt before putting in the fridge. This will help the chicken be more flavorful and tender.
Do not rinse your chicken before you marinate it.
Buttermilk: You can make your own buttermilk with milk and vinegar or lemon. However in this case I recommend that you use true buttermilk.