01 - Preheat a grill or grill pan over medium-high heat.
02 - Brush chicken breasts with 1 tablespoon olive oil and season both sides generously with salt and pepper.
03 - Place chicken on the grill and cook for 5 to 6 minutes per side, or until cooked through and juices run clear. Remove from heat and let rest for 5 minutes before slicing thinly.
04 - While chicken rests, arrange plum halves cut-side down on the grill. Cook for 2 to 3 minutes until lightly charred and softened. Remove and set aside for slicing.
05 - In a small bowl, whisk together extra virgin olive oil, balsamic vinegar, honey, Dijon mustard, salt, and pepper until emulsified.
06 - In a large salad bowl, combine spinach, basil, grilled plums, sliced chicken, feta cheese, and pecans.
07 - Drizzle the dressing evenly over the salad and toss gently to coat all ingredients. Serve immediately, garnishing with additional fresh basil if desired.