Preheat your grill or stovetop grill pan over medium-high heat. Season the chicken breasts with salt, pepper, and olive oil.
Grill the chicken for about 6-7 minutes on each side, or until the internal temperature reaches 165°F. Remove from the grill and let it rest for 5 minutes before slicing.
In a large bowl, combine the cooked quinoa, basil pesto, cherry tomatoes, baby spinach, and lemon juice. Toss until everything is well mixed.
Divide the quinoa mixture into serving bowls. Top each bowl with sliced grilled chicken and sprinkle with grated Parmesan cheese.
Serve immediately and enjoy your flavorful bowl!