1. Prepare Oven and Baking Dish:

• Preheat the oven to 400°F (200°C).
• Spray a 9×13 inch baking dish (or similar size that fits the chicken) with cooking spray or lightly grease with oil.

2. Prepare and Season Chicken:

• Place the chicken breasts in the prepared baking dish, ensuring they are in a single layer. If using thicker breasts, consider pounding them to an even 1/2 to 3/4 inch thickness first.
• Sprinkle both sides of the chicken breasts generously with salt and black pepper.

3. Layer the Toppings:

• Spread the BBQ sauce evenly over the top of the chicken breasts using a spoon or brush.
• Top the BBQ sauce evenly with the diced pineapple chunks.
• Sprinkle the cooked, diced bacon over the pineapple.
• Scatter the thinly sliced red onion over the bacon.
• Finally, top everything evenly with the shredded mozzarella cheese.

4. Bake:

• Place the baking dish in the preheated oven.
• Bake uncovered for 25-30 minutes, or until the chicken is cooked through (internal temperature reaches 165°F/74°C) and the juices run clear. The cheese should be melted and bubbly.

5. Broil (Optional):

• For extra golden, crispy cheese, carefully switch the oven setting to Broil (High) after the chicken is cooked.
• Broil for 3-4 minutes, watching constantly to prevent burning, until the cheese is bubbly and browned to your liking.

6. Garnish and Serve:

• Remove the dish from the oven and let it rest for a few minutes.
• Top with additional diced pineapple and diced green onions before serving for freshness and color.
• Serve warm.