Peel onion and slice into 1/4" rounds. Quarter pear, core, and cut into 1/4" slices. Whisk together balsamic vinegar and honey in a large mixing bowl. Pat chicken breasts dry, and season both sides with a pinch of salt and pepper.

Place onion rounds on prepared baking sheet and separate rounds into rings. Drizzle with 1 Tbsp. balsamic-honey mixture (reserve remaining for vinaigrette) and spread into a single layer. Roast until onions are softened, 15-18 minutes. While onions roast, cook chicken.

Drizzle chicken with 1 tsp. olive oil and place on hot grill. Grill until chicken reaches a minimum internal temperature of 165 degrees, 5-6 minutes per side. Remove chicken from grill and let rest 5 minutes.

Whisk 1 Tbsp. olive oil into reserved balsamic-honey mixture and add 1/4 tsp. salt. Taste, and season to taste with salt and pepper. Salt will highlight the sweetness and sharpness of balsamic and honey. Heat a small pan over medium heat. Add walnuts to hot, dry pan and stir constantly until toasted and aromatic, 4-5 minutes. Remove walnuts from pan and set aside.

Add spinach to bowl with balsamic vinaigrette. Toss to combine and season with 1/4 tsp. salt and a pinch of pepper. Alternatively, serve dressing on side to control amount.

Slice chicken if desired. Place a serving of salad on a plate and top with separated rings of roasted onion and pear. Garnish with goat cheese crumbles (breaking up with your hands if needed), toasted walnuts, and dried cherries. Serve chicken next to salad or on top.