Mix together the jerk seasoning: garlic powder, onion powder, coconut sugar, paprika, cumin, thyme, allspice, cinnamon, cayenne pepper, sea salt, and black pepper. Generously rub on both sides of the chicken.
Heat a cast iron skillet to medium high heat for three minutes. Once hot, add the oil and warm for 30 seconds.
Place the chicken in the hot skillet. Sear for 2 minutes, then flip. If chicken is "stuck" wait another 30 seconds, and try again (it might not be ready to flip!). Now cover with a lid and reduce heat to medium low. Cook for 10-12 minutes, or until internal temperature reaches 165F. Remove chicken from the skillet and let rest on the cutting board for at least 5 minutes until slicing.
Meanwhile, make the salsa. Toss together the pineapple, tomatoes, onion, cilantro, lime juice, jalapeno pepper (if using), and sea salt. Spoon on top of the chicken and serve!