1. Season each chicken breast with salt and pepper. In a large, oven-proof skillet, heat 1 T olive oil and sear the chicken 2 to 3 minutes on each side until lightly golden. Place in pan and bake 15 minutes at 375 degrees.
2. While chicken is cooking, heat 1 T olive oil in a large pan over medium heat and saute red onion until softenend; 2-3 minutes. Add spinach and toss until wilted. Season with salt and pepper and transfer to a large platter or divide evenly between 4 plates.
3. Wipe out pan and heat remaining 1 T olive oil with vinegar. Add pears and gently heat to warm. Stir in parsley.
4. Place cooked chicken breasts on spinach. Top with pear slices and about 2 T blue cheese per breast.