Preheat oven to broil.

Brush chicken breasts with a little olive oil and season with salt and pepper well.

Heat a grill pan over medium/high heat. Grill chicken about 4 minutes per side or until cooked through. Remove from grill and set aside.

Add onions to grill pan and soften for 3-4 minutes. Set aside.

Slice rolls open and place cut side up on a baking sheet. Brush cut side with olive oil and broil just until slightly brown, about 2 minutes.

To assemble sandwich layer ingredients on bottom of roll in this order:

Pesto, onions, bacon, chicken, sun dried tomato, spinach, mozzarella and top with top of roll. Place back under the broiler for 2-3 more minutes, just to soften the cheese.

Serve warm.