Preheat oven to 350F
Season each chicken breast with salt and pepper to taste on both sides. Set aside.
In a large bowl, stir together the hot cooked rice, cilantro, cream cheese, taco seasoning, 1 cup Mexican blend cheese, 2 tablespoons enchilada sauce, tomatoes, and onion. Stir until fully combined and the cream cheese is melted and incorporated (microwave a bit if necessary).
Cut each chicken breast lengthwise, as deep as possible. You want as big of a pocket to stuff with the rice as you can get without cutting fully in half.
Stuff each breast with 1/4 of the rice mixture, pushing the rice as much to the back of the pocket as you can. If you'd like, you can seal the breasts with toothpicks, but that is optional (and if you add them, be sure to remember they're there before eating!) If you don't seal them, some rice may come out while cooking, which is totally fine.
Heat a large skillet over medium high heat. Add 2 tablespoons enchilada sauce and 1 tablespoon olive oil.
Add the chicken to the skillet and sear both sides for 5-6 minutes each.
Remove from the heat and cover the chicken with the remaining enchilada sauce, and remaining 1 cup cheese.
Bake the chicken uncovered in the oven for 10-12 minutes or until the chicken is fully cooked through.
If you sealed with toothpicks, remove before eating.
Serve and enjoy!