Preheat oven to 425°F
Place thin-cut chicken breasts in a baking dish
Season both sides with garlic salt and black pepper
Brush Dijon mustard evenly over the tops of the chicken
Sprinkle Monterey Jack cheese over each piece
Top with crumpled crispy fried onions, pressing lightly so everything sticks
Bake uncovered for 15–20 minutes, or until chicken reaches 165°F internal temperature
