Preheat the oven to 375°F.

Lightly spray a 9×13 baking dish.

Fill a medium-sized saucepan about ¾ full with water. Bring to a low rolling boil, then add the elbow macaroni. Cook until the macaroni is done, then drain and set aside.

In a medium-sized skillet, add the butter and diced onions. Cook over medium-high heat, stirring with a wooden spoon for even cooking, for about 5 to 7 minutes. The onions should be translucent and just starting to turn golden. Remove from the heat and set aside.

In a medium-sized mixing bowl, add the softened cream cheese, cream of chicken soup, sour cream, milk or half and half, and the package of ranch dressing powder.

Using a handheld mixer, combine the sour cream mixture on medium speed until smooth and creamy.

Reduce the speed to low and add the kosher salt, black pepper, and onion powder. Mix until well combined.

Transfer the sour cream mixture to a large mixing bowl. Add the cooked macaroni, cubed chicken breast, cooked yellow onion, 1½ cups of cheddar cheese, and ¾ cup of cooked bacon. Using a large wooden spoon, stir until all the ingredients are evenly combined.

Pour the chicken mixture into the prepared baking dish and spread evenly.

Sprinkle the remaining shredded cheddar cheese, bacon, and thinly sliced green onion over the top.

Bake for 35 to 40 minutes, until the top layer of cheese is melted and gooey.