Preheat a grill pan over medium-high heat.
Place the chicken tenders in a shallow dish and season with salt and pepper.
Drizzle with olive oil and toss until evenly coated.
Grill the chicken for 3–4 minutes per side, or until fully cooked and no longer pink inside.
Transfer the chicken to a cutting board and let it rest for several minutes before slicing.
In a small bowl, whisk together the yogurt, chives, garlic, olive oil, salt, and pepper until smooth.
Arrange the chopped romaine lettuce on a serving platter.
Top the lettuce with rows of sliced grilled chicken, hard-boiled eggs, cherry tomatoes, cucumber, avocado, and red onion.
Sprinkle with crumbled blue cheese and additional chopped chives.
Drizzle the homemade ranch dressing over the Chicken Cobb Salad just before serving.