Prepare the Chicken: Preheat the grill or grill pan over medium-high heat. Pat the chicken breasts dry with paper towels, then brush with olive oil. Season both sides with garlic powder, onion powder, paprika, salt, and pepper.
Grill the Chicken: Place the chicken on the preheated grill and cook for 5-7 minutes per side or until the chicken reaches an internal temperature of 165°F (75°C). Remove the chicken from the grill and set aside to rest for a few minutes.
Assemble the Dish: While the chicken rests, slice the California avocados and drizzle with lime juice to prevent browning.
Top the Chicken: Once the chicken is rested, place slices of avocado on top of each chicken breast. If desired, sprinkle shredded mozzarella cheese on top and return to the grill for 1-2 minutes to melt the cheese.
Garnish and Serve: Garnish with fresh cilantro and serve immediately.