Prepare the chicken: Season chicken breasts with salt, pepper, garlic powder, and paprika.
Grill the chicken: Heat grill or grill pan to medium-high. Cook chicken about 6-7 minutes per side until internal temperature reaches 165°F (74°C). Let rest 5 minutes.
Prep the vegetables: Wash and dry Romaine and mixed greens. Slice cherry tomatoes, cucumber, and red onion.
Make the dressing: Whisk together olive oil, red wine vinegar, Dijon mustard, honey, salt, and pepper.
Assemble the salad: In a large bowl, combine greens, tomatoes, cucumber, and onion. Toss gently with dressing.
Slice chicken: Cut rested chicken into thin strips.
Add toppings: Top salad with shredded cheese, croutons, and sliced chicken. Toss lightly or serve with chicken on top.
Serve immediately.