Season the chicken breasts with salt, pepper, cumin, and chili powder. Heat olive oil in a large skillet over medium heat. Add the chicken and cook for 6-7 minutes on each side until fully cooked and golden brown. Remove from the skillet and set aside. In the same skillet, add the rice and sauté for 1-2 minutes until lightly toasted. Pour in the chicken broth and diced tomatoes (if using). Bring to a boil, then reduce heat, cover, and simmer for 15-18 minutes until the rice is tender and liquid is absorbed. While the rice cooks, warm the queso blanco in a small saucepan or microwave until smooth and creamy. Once the rice is done, slice the cooked chicken and serve it over the rice. Drizzle with warm queso blanco and garnish with fresh cilantro.