Season the chicken breast with salt and pepper. Heat a skillet over medium-high heat and add oil. Cook the chicken for about 6-7 minutes on each side or until cooked through and golden brown. Remove and let rest before slicing into strips.

In the same skillet, reduce the heat to medium, add sliced onions, and sauté for about 5-7 minutes until soft and golden brown. Set aside with the cooked chicken.

Return the chicken to the skillet, layer with cheese, cover, and reduce heat to low. Let cheese melt for about 2-3 minutes.

Toast hoagie rolls in a separate pan over medium heat for about 2-3 minutes until crisp and golden.

Slice open toasted hoagie rolls and fill with cheesy chicken and caramelized onions. Serve warm.