Barbecued Chicken Panini

2 boneless, skinless chicken breast halves
1/4 cup olive oil
Kosher salt and pepper
1/2 cup smoky bacon barbecue sauce
1 large red onion, cut into 1/4-inch rings
1 large piece focaccia (8"x7")
8 slices provolone cheese

Preheat a panini press to 375.

Rub the chicken breast on both sides with 1 Tbsp of olive oil and season with salt & pepper. Place the chicken on the panini press, close the lid and cook until nicely grilled-marked, about 6 minutes. Turn chicken over and continue cooking until chicken is cooked through, about 5 minutes more. Transfer the chicken to a cutting board and cut into 1-inch pieces. Transfer to a bowl and combined with barbecue sauce.

Reduce heat on the panini press to the lowest setting. In another bowl, stir together the onion rings, 2 Tbsp of olive oil, 3/4 tsp salt and a pinch of pepper. Arrange the onion rings on the panini press, close the lid and cook, stirring occasionally, until they are soft and golden, 12 to 14 minutes. Transfer to a bowl.

Wipe the panini press clean and increase the heat to 400. Cut focaccia in half horizontally. Brush the outside of the focaccia halves with the remaining olive oil.
Place the bottom half, cut side up, arrange the chicken in an even layer on top and top with onions & cheese. Cover with the top half of the focaccia, cut side down. Close the lid on the panini press and cook until cheese melted, about 6 minutes.