Start by trimming any excess fat from the lean chicken breasts. In a bowl, combine the chicken with olive oil, garlic powder, smoked paprika, salt, and pepper, ensuring each piece is well-coated. Marinate for at least 10 minutes.

Heat a grill pan over medium-high heat until hot, about 3-4 minutes. Place the marinated chicken on the grill pan, cooking for 6-7 minutes on each side until the internal temperature reaches 165°F (74°C). Remove from heat and let it rest for 5 minutes before slicing.

While the chicken is resting, prepare either brown rice or quinoa according to the package instructions, usually taking about 15-20 minutes.

Rinse and drain the black beans, halve the cherry tomatoes, dice the red onion, and shred the lettuce. If using frozen corn, heat it until warm.

In four bowls, divide the grains as the base. Arrange the veggies around the edges, and place the sliced chicken in the center. Drizzle with BBQ sauce and ranch dressing, garnish with cheese and cilantro if desired.