01 - Bring a large pot of salted water to a rolling boil. Add pasta and cook according to package directions until al dente. Drain well, rinse under cold running water to halt cooking, and set aside to cool completely.
02 - Season chicken breasts evenly with garlic powder, salt, and black pepper. Heat olive oil in a large skillet over medium heat. Sear chicken for 6 to 7 minutes per side until golden brown and internal temperature reaches 165°F. Transfer to a cutting board and rest for 5 minutes before cutting into bite-sized cubes.
03 - In a medium mixing bowl, combine mayonnaise, Dijon mustard, honey, apple cider vinegar, and olive oil. Whisk vigorously until smooth and emulsified. Season with salt and pepper, then taste and adjust as needed.
04 - In a large serving bowl, combine the cooled pasta, diced chicken, halved cherry tomatoes, cucumber, red bell pepper, red onion, and baby spinach. Pour the honey mustard dressing over the top and toss gently until every component is evenly coated.
05 - Garnish with fresh herbs if desired. Serve immediately at room temperature, or refrigerate for 1 hour to allow the flavors to meld before serving.