Creating the Chicken Avocado Melt Sandwich is simple if you follow these steps:

1. Prepare the Chicken: Season the chicken breasts with olive oil, garlic powder, salt, and black pepper.
2. Grill the Chicken: Heat a grill pan over medium heat. Cook the chicken for about 6-7 minutes on each side or until fully cooked and no longer pink in the center. Remove from heat and let it rest for a few minutes.
3. Toast the Bread: While the chicken is resting, toast the slices of bread on the grill pan until golden brown.
4. Slice the Chicken: Once the chicken has rested, slice it thinly.
5. Assemble the Sandwich: On one slice of toasted bread, layer the sliced chicken, avocado, and cheese. If desired, add lettuce and tomato slices.
6. Melt the Cheese: Place another slice of toasted bread on top. Return the sandwich to the grill pan and cook for 2-3 minutes on each side, pressing down slightly, until the cheese is melted and the bread is golden brown.
7. Serve: Remove from the pan and cut the sandwich in half. Serve warm.