Quarter apple and remove core. Cut into thin slices. Trim ends off celery and cut into thin slices on an angle. Mince chives. Coarsely chop almonds. Mix 1 Tbsp. water and cornstarch in a mixing bowl. Pat chicken breasts dry, and season with ¼ tsp. salt and a pinch of pepper.

Place a medium non-stick pan over medium-high heat. Add 1 tsp. olive oil and chicken to hot pan. Cook until browned, 1-2 minutes per side. Transfer to prepared baking sheet. Roast until chicken reaches a minimum internal temperature of 165 degrees, 8-10 minutes. Wipe pan clean and reserve. While chicken roasts, make sauce.

Return pan used to sear chicken to medium-high heat. Add cream and a pinch of salt, bring to a boil, and add cornstarch slurry. Return to a boil and cook until sauce slightly thickens, 1 minute. Remove from burner, and stir in Parmesan until smooth. Add half the chives (reserve remaining for garnish). If sauce is too thick, add water 1 Tbsp. at a time until desired consistency is reached.

Combine vinegar, 2 tsp. olive oil, and a pinch of salt and pepper in another mixing bowl.

Add apple, celery, and arugula to mixing bowl with dressing. Toss to combine. Alternatively, serve dressing on side to control amount.

Place chicken on a plate. Pour sauce over chicken. Garnish with remaining chives. Place salad next to chicken and garnish with almonds.