In a small bowl, combine the flour, onion powder, garlic powder, salt, and pepper. Set aside.
Season the chicken breasts lightly with kosher salt and black pepper.
Heat the olive oil in a large skillet over medium heat. Cook the chicken breasts for about 5 minutes on each side, or until the internal temperature reaches 165°F.
Remove the cooked chicken from the pan and set aside.
Reduce the heat to medium-low. Add the butter and chicken base to the skillet, stirring until melted.
Sprinkle in the flour mixture and stir well to form a roux. Cook while stirring continuously for 30 seconds to 1 minute.
Gradually pour in the chicken stock, scraping up any browned bits from the bottom of the pan. Add the water and whisk thoroughly to prevent lumps. Let the mixture simmer until it thickens to your desired consistency.
If using, stir in the heavy cream.
Shred the chicken if you like, then return it along with any collected juices to the skillet. Let everything simmer together for a few minutes.
Taste the gravy and adjust seasoning if necessary.
Serve over mashed potatoes, egg noodles, or rice.