Preheat your oven to 375°F (190°C). If your chicken breasts are very thick, you can pound them slightly to an even thickness for more consistent cooking. Alternatively, you can cut thicker breasts in half horizontally to create thinner cutlets. Place the chicken breasts in a greased 9x13 inch baking dish. Season both sides of the chicken with salt and pepper.

In a medium bowl, combine the undrained can of Rotel diced tomatoes with green chilies, softened cream cheese cubes, shredded Monterey Jack cheese, shredded cheddar cheese, sour cream, milk (or heavy cream), garlic powder, and onion powder.

Whisk all the ingredients for the queso sauce together until the cream cheese is mostly incorporated and the mixture is relatively smooth. Don't worry if there are a few small lumps of cream cheese; they will melt in the oven.

Pour the prepared queso sauce evenly over the chicken breasts in the baking dish. Ensure each piece of chicken is well-coated with the delicious cheesy mixture.

Cover the baking dish tightly with aluminum foil. Bake for 25-30 minutes, or until the chicken is mostly cooked but not yet fully tender.

Remove the foil and continue to bake for another 10-15 minutes, or until the chicken is cooked through (internal temperature of 165°F or 74°C) and the queso sauce is bubbly and slightly golden brown around the edges. You can also broil for the last 1-2 minutes for extra browning if desired, but watch it closely to prevent burning.

Let the Baked Queso Chicken rest for about 5 minutes before serving. This allows the juices to redistribute in the chicken and for the sauce to settle slightly.