Preheat your outdoor grill over high heat. We have a Traeger Grill and I set it to 475ºF. You could also cook this in your oven at 425ºF. Set your cast iron skillet in your grill (or oven) to heat up with the grill (or oven).
Season the chicken on both sides generously with salt and pepper. In a small mixing bowl, toss the tomatoes in olive oil and season with salt + pepper.
When your grill (or oven) is heated, place your chicken breasts skin side DOWN in the skillet. Then pour over the tomatoes.
Cook for 25-30 minutes, until the chicken has an internal temperature of 165ºF and the tomatoes are blistered. No need to flip the chicken. I leave it skin side down the whole time so the skin gets crispy and golden brown.
While the chicken is cooking, make the basil butter. In a small mixing bowl, combine the ghee, basil, lemon zest and garlic. Mash with a fork until fully combined.
Serve the chicken breasts warm topped with 1 tablespoon of the basil butter, along with the blistered tomatoes. I like topping the blistered tomatoes with more finely chopped basil. Delicious with cauliflower rice!
Leftovers will keep in an airtight container refrigerated for at least 5 days.