Preheat your grill or grill pan to medium-high heat.
In a small bowl, mix together olive oil, garlic powder, onion powder, salt, and pepper. Brush this mixture over the chicken breasts.
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.
While the chicken is resting, steam the broccoli florets until tender, about 5 minutes.
In a separate bowl, combine Greek yogurt, mayonnaise, minced garlic, lemon juice, and dried parsley. Mix until smooth to create the creamy garlic sauce.
To assemble the bowls, start with a base of cooked brown rice, add sliced grilled chicken and steamed broccoli, and drizzle with the creamy garlic sauce.
Sprinkle grated Parmesan cheese on top before serving.