In a large glass bowl, whisk together brown sugar BBQ grill seasoning, olive oil, apple cider vinegar, 1/2 c. Coca-Cola, red pepper flakes, and paprika.

Set aside 1/4 c. marinade.

Add chicken breasts to remaining marinade in glass bowl, stir to coat, and cover bowl with foil.

Place in the refrigerator to marinate for about 2 hours.

Meanwhile, add remaining Coca-Cola to a large saucepan.

Bring to a simmer over medium heat.

Simmer for about 1 hour, stirring occasionally, or until it thickens into a syrupy consistency, and reduces to about 1/2 cup. As the soda reduces, it will need more attention and stirring. It takes a while to significantly reduce, about 45 minutes, but then reduction happens quite quickly. Pay particular attention to the soda during the last 10-15 minutes of the reduction process.

Whisk in butter and salt.

Remove from heat, and carefully pour into a jelly jar or heat-proof glass jar.

Add reserved marinade to the Coca-Cola reduction, and stir to combine.

Remove chicken from refrigerator, and discard that marinade.

Grill chicken for 5-7 minutes on each side, basting with Coca-Cola mixture, or until internal temperature reads 165 degrees Fahrenheit.

Serve!