Place the grape tomatoes into the cast iron skillet then drizzle with olive oil and season with sea salt and freshly cracked pepper, to taste. Place into the oven and roast for 13-15 minutes, or until just starting to blister. They will continue to cook later with the chicken.
While tomatoes roast, dry chicken thighs with paper towels as much as possible. Season skin side generously with garlic powder, sea salt, and freshly cracked pepper, to taste.
Once the tomatoes have roasted, remove the skillet from the oven, making sure to keep the oven on 400 degrees. Place the skillet on the stove over medium-high heat. Remove tomatoes and set aside.
Add a light coating of olive oil to the cast iron skillet. Add the chicken thighs, skin side down, to the HOT skillet. Season the other side garlic powder, sea salt, and freshly cracked pepper, to taste. Cook 3-4 minutes, or until the chicken turns easily and is golden brown. Flip the chicken and sear the bottom side for about 1 minute. Remove chicken from pan and set aside on a plate.
With the cast iron skillet still on medium-high heat, add the shallot. Cook, stirring constantly, for 1 minute. Add the minced garlic and cook, stirring constantly, for 1 minute. Add 1/2 cup of white wine; cook and scrape up any browned bits from the bottom of the skillet for 1 minute. Add the 1/2 cup chicken broth and lemon juice to the skillet. Add the blistered grape tomatoes and their juices back to the skillet. Taste and season with a bit of sea salt and freshly cracked pepper, to taste, if needed. Nestle the chicken thighs skin side up into the sauce with the tomatoes.
Place into the oven and bake for 30-35 minutes, or until the chicken is cooked through.
Remove and top with fresh basil. Serve with tomatoes and sauce. Enjoy!