Heat 1 tbsp butter in a large pan on medium heat.
Sauté green peppers and onions until tender but not brown, about 5 minutes. Set aside.
Add the remaining tbsp butter to the sauté pan.
Brown chicken breasts on one side over medium-high heat.
Flip the breasts over and add the garlic to the pan. Cook the garlic until lightly golden and brown the other side. *If you have large breasts, do this in two batches so the breasts have room to sear.
Spray the crockpot with cooking spray.
Then add the chicken and garlic, seasonings, pineapple, BBQ sauce, green peppers, and onions.
Stir all together and cook on LOW for 6-7 hours, depending on the size of the breasts. *see tips
Rest 5-10 minutes, shred, and serve.