Prepare poblano peppers according to instructions above. Chop and set aside.
Preheat oven to 350°F.
Place chicken breasts on a plate or cutting board.
Season both sides of the chicken breasts with seasoned salt, black pepper and garlic powder.
Place chicken breasts on pan. Place in oven and cook for about 16 minutes on one side.
Pour olive oil into a large skillet.
Place pan over medium heat. Heat until oil is hot and shimmering.
Add onions. Cook, stirring constantly, until onions are very caramelized and slightly crispy. Remove from heat.
After cooking the chicken the first 16 minutes, pull pan out and flip the breasts over.
Spoon 1/4 of prepared onions onto each chicken breast.
Spoon 1/4 of tomatoes onto each chicken breast.
Spoon 1/4 of prepared poblano peppers onto each chicken breast.
Place 1 or 2 Jack cheese slices on each chicken breast.
Return pan to the oven. Cook for another 12 to 14 minutes or until the chicken is done through and inside reaches a temperature of at least 165°F.
Remove from oven.
Place chicken breasts on a serving platter or individual serving plates.
Garnish with avocados, cotija cheese and cilantro.
Serve hot.