Cut the chicken breasts into uniform 1-inch chunks to ensure even cooking throughout the slow cooker. Dice the red onion into 1/2-inch pieces and chop the bell peppers into bite-sized chunks (roughly 3/4 to 1 inch). If using fresh pineapple, cut into chunks; if using canned, drain the pineapple and reserve the juice separately. Having everything prepped and ready makes assembly quick and ensures consistent cooking.

Add the cut chicken, peppers, onion, and pineapple directly to your slow cooker. Sprinkle the salt, pepper, and garlic powder evenly over the ingredients and stir gently to distribute seasonings. Pour in 1/2 cup of BBQ sauce and stir until everything is coated. I like to add the seasonings before the sauce so they distribute more evenly rather than clumping with the sauce.

Cover the slow cooker and cook on low for 6-7 hours, or on high for 3-4 hours if you're short on time. The chicken will be tender and the flavors will meld together beautifully. You don't need to stir it during cooking—the slow cooker does the work for you.

After the cooking time is complete, carefully drain any excess liquid from the slow cooker using a colander or by tilting the lid slightly and pouring off the liquid. This prevents the dish from being watery. Stir in the remaining 1/2 cup of BBQ sauce to create a thick, glossy coating on the chicken and vegetables.

Transfer the chicken and pineapple mixture to a serving dish or individual bowls. Thinly slice the green onions on a bias for a professional presentation and scatter them over the top just before serving. The fresh green onion garnish adds a bright contrast to the sweet and smoky BBQ flavors.