Prepare poblano peppers, then chop them and set aside.
Preheat the 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.
Put chicken breasts in a pan and bake for 16 minutes on one side.
Heat olive oil in a large skillet over medium heat until hot.
Add onions and cook until caramelized and slightly crispy, stirring constantly. Remove from heat.
After the first 16 minutes of chicken cooking, flip the breasts.
Spoon 1/4 of caramelized onions, tomatoes, and prepared poblano peppers onto each chicken breast.
Lay 1 or 2 slices of Jack cheese on each chicken breast.
Return the pan to the oven. Bake for 12 to 14 minutes or until chicken reaches 165°F.
Take it out of the oven.
Place chicken breasts on a serving platter or individual plates.
Garnish with avocados, cotija cheese, and cilantro.
Serve while hot.